Patent Grant
7151943
The present invention relates generally to data communications systems and more particularly relates to protocols for communicating with a programmable logic control device by sending a data sequence, typically one or more pages, via a forward overhead control channel of a cellular network control channel for a cellular mobile radiotelephone system.
In recent years, the communications industry has shown a growing interest in various types of wireless communications systems for communicating voice and/or data between numerous remote sites and a central location. It is well recognized that the use of a dedicated telephone facility for a conventional telephone system is not a convenient or economical option for all communications applications. For example, for many industrial applications, a central data collection site has a need for acquiring information from a variety of remotely located monitoring devices that collect data about the operation or performance of equipment. To overcome the limitations of the conventional telephone system, a two-way wireless communications link is often necessary to permit a response to a communication initiated from another location. In an attempt to solve the problem of supplying a response to an initial communication, the industry has offered various wireless communications systems, including two-way radios, cellular mobile radiotelephones, and paging systems.
To overcome the limitations of prior communications systems, the assignee for the present invention has developed a system for communicating data via a cellular network control channel of a cellular mobile radiotelephone (CMR) system. U.S. Pat. Nos. 5,526,401, 5,546,444, and 5,873,043, which are assigned to the assignee for the present application and contain subject matter fully incorporated herein by reference, describe an adapted use of the existing architecture of a CMR system in an efficient and cost-effective manner to support communications via the CMR system, including collection and reporting of data obtained at remote sites.
The data message system described in the referenced U.S. patents includes data reporting devices, at least one mobile switching center (MSC), and a data collection system connected directly or indirectly to the MSC or a Signal Transfer Point (STP). The MSC can issue commands or instructions, typically in a sequence of page messages, to the data reporting devices via the cellular network control channel of the CMR system. Each data reporting device can monitor the operation of a remote data source to collect selected data or can control the operation of a remote item in response to commands transmitted over the via the MSC. The data reporting device can transmit a data message containing the selected data via a cellular network control channel of the CMR system when the data reporting device first identifies itself or “registers” for operation with the MSC. Alternatively, the data reporting device can send the selected data via the cellular network control channel in a data message formatted to represent a “call origination” signal. In turn, the MSC can send the data message to the data collection system via a communications link. In this manner, the data message system takes advantage of an installed base of cellular communications equipment by using the cellular network control channel for data communications between a central location and one or more remote sites.
The data reporting device of the data message system typically communicates with the MSC via the reverse overhead control channel (RECC) of the cellular network control channel. In contrast, the MSC can communicate with a cellular-compatible device, such as a data reporting device, via the forward overhead control channel (FOCC) of the cellular network control channel. The conventional technique for sending a message to a cellular mobile radiotelephone from an MSC is the transmission of a page message over the FOCC. For example, a conventional cellular mobile radiotelephone can be stimulated by a transmission of the MSC to locate the mobile telephone unit when an incoming call from a landline has been placed to this unit. The data requirement for this type of trigger message is minimal for conventional cellular communications and, consequently, each message is independently processed as a complete data packet. This works well for the paging operations conducted by an MSC with conventional cellular mobile radiotelephones via the FOCC. However, this mechanism significantly limits the amount of information or instruction that can be provided by the MSC to a data reporting device via a page carried by the cellular network control channel. This is a disadvantage for applications requiring the communication of a commands and/or data via the CMR system to a remote cellular communications device for use by a controller, such as a programmable logic controller (PLC), coupled to a controllable item or instrument.
In view of the foregoing, there is a need for adapting the paging mechanism of a CMR system to support the transfer of commands and/or data for communications from an MSC to a cellular-compatible device. There is a further need for communicating with and controlling the operations of a remote controller, such as a PLC, coupled to a cellular-compatible device that can accept commands and/or data via the paging mechanism of a CMR system.
The present inventions solves the needs of the prior art by providing a method for communicating with cellular communication devices by sending multiple pages via a cellular network control channel of a cellular mobile radiotelephone (CMR) system. Each cellular communications device operating within the coverage area of the CMR system can monitor the Forward Overhead Control Channel (FOCC) of the cellular network control channel for a pair of pages, commonly described as target pages, within a first time period. Each target page includes a specific identifier assigned to one or more of the cellular communications devices. Each cellular communications device maintains a mask in memory for storing one or more specific identifiers assigned to that device. In the event that a cellular communications device receives a page, such as the target page, having a matching specific identifier, the device will complete an action responsive to that page. Otherwise, a cellular communications device will ignore a page having a specific identifier that does not match an identifier assigned to that device.
In response to receiving a pair of pages having a matching specific identifier within the first time period, typically 60 seconds, the cellular communications device monitors the cellular network control channel over a second time period for at least one data page having a predetermined characteristic designating the page as carrying data. For a data page formatted as a cellular telephony signal having a Mobile Identification Number (MIN) field, the predetermined characteristic can be defined as a 2, 3, 4, 5 or 6 positioned in the least significant digit (LSD) of the MIN carried by that page.
In response to receiving at least one data page having a predetermined characteristic during the second time period, the cellular communications device can collect the data carried by the received data page. This data can be stored at the cellular communications device for subsequent use or is forwarded for processing by another device, such as a programmable logic controller (PLC). To acknowledge receipt of the data, the cellular communications device can send an acknowledgement signal via the cellular network control channel. This acknowledgement signal can be formatted as a cellular telephony Autonomous Registration signal and carries an indication of data verification. A mobile switching center (MSC) typically receives the acknowledgement signal via the Reverse Overhead Control Channel (RECC) of the cellular network control channel.
For one aspect of the invention, the cellular communications device can continue to monitor the FOCC for a second consecutive data page if the predetermined characteristic in the first received data page specifies that a pair of consecutive pages carry data. This monitoring operation is typically carried out over the second time period. If the second data page is received during the second time period, then the cellular communications device can collect the data carried by both the first and second pages. The combination of data collected from the first and second pages can be forwarded by the cellular communications device to the PLC via a wired or wireless communications link. The cellular communications device can verify receipt of the data carried by both pages and issue an acknowledgement signal via the RECC to acknowledge receipt of such data. This acknowledgement signal can be formatted as an Autonomous Registration signal comprising an Acknowledge Pattern (AAA hex) within the upper 12 bits and collected data, represented in BCD, big-endian order format, within the lower 12 bits.
For another aspect of the invention, a cellular communications device can terminate monitoring operations prior to expiration of the second time period if the predetermined characteristic in the first received data page specifies that only a single page carries data. The cellular communications device can collect the data carried by the first data page and issue an acknowledgement signal via the RECC to acknowledge receipt of the data carried by that page. This acknowledgement signal can be formatted as an Autonomous Registration signal comprising an Acknowledge Pattern (AAAAAA hex) within the upper 24 bits and collected data represented in BCD, big endian order format, within the lower 8 bits.
The present invention also provides a method for communicating a programming command to a controller, such as a PLC, by sending multiple pages via the cellular network control channel of a CMR system. The PLC is typically coupled to a cellular communications device via a wired or wireless communications link. The cellular communications device can monitor the FOCC of the cellular network control channel for a target page having a specific identifier assigned to that communications device. Timely receipt of one or more target pages having a specific identifier assigned to the cellular communications device within a predetermined time period prompts that device to monitor the FOCC for a schedule page.
In response to receiving the target page(s), the cellular communications device can monitor for a time period the FOCC for a schedule page having a schedule command. The schedule command identifies a slot number in a look-up table maintained in memory by the PLC. This slot number represents a specific storage location within the look-up table for maintaining a programming command for the PLC.
In response to receiving the schedule page during the time period, the cellular communications device can forward the slot number to the PLC via the communications link. In turn, the PLC can retrieve from its look-up table the programming command identified by the slot number and initiate a program action associated with that programming command. The cellular communications device also can send an acknowledgement signal via the cellular network control channel to acknowledge receipt of the schedule command.
The present invention further provides a method for communicating a reprogramming command to a PLC by sending multiple pages via a cellular network control channel of the CMR system. A cellular communications device, which is coupled to the PLC, monitors the FOCC for one or more target pages having a specific identifier assigned to that device. In response to receiving target page(s) with a matching specific identifier during a time period, the cellular communication devices monitors the FOCC for a schedule page having a schedule command. The schedule command identifies a slot number specifying a particular stock in the PLC's look-up table containing programming data. In response to receiving the schedule page during a time period, the cellular communications device monitors the FOCC for a data page carrying new programming data. Responsive to receiving the data page, the cellular communications devices forwards to the PLC the slot number and the new programming data. In addition, the cellular communications device sends an acknowledgement signal via the cellular network control channel to acknowledge receipt of the slot number and programming data.
In view of the foregoing, it will be understood that a cellular communications device operating within the coverage area of a CMR System can receive multiple pages via the FOCC and provide data extracted from one or more of these pages to a controller, such as PLC. The PLC, which is typically coupled to a controllable instrument, can accept the extracted data as programming data representing new or replacement program commands. In contrast to the prior art, the communication of programming data to a PLC requires the reception of multiple pages by a cellular communications device via the FOCC. These and other objectives of the present invention will become evident upon a review of the detailed description, the drawing set and the appended claim set.
The present invention is directed to a system for communicating with a cellular communications device by sending one or more paging messages, commonly described as pages, via a cellular network control channel of a cellular mobile radiotelephone (CMR) system and using data of the received pages to control the operations of a remote controller. Although a conventional cellular device can receive and process discrete pages transmitted over a forward overhead control channel (FOCC) of the cellular network control channel, the present invention provides the advantage of communicating commands (and data) to a cellular-compatible device for use in connection with a controller, such as a programmable logic controller (PLC) device, that controls a field instrument. This adds a new communication function for a device capable of monitoring the cellular network control channel because selected pages can be received and processed to achieve remote control over the operations completed by the controller on behalf of a controlled instrument. It will be appreciated that the cellular-compatible device can be integrated within the assembly of the PLC device or housed in an assembly separate from the PLC device.
The data communication capacity offered by the present invention supports the transmission and processing of data and commands or instructions, whereas a prior paging mechanism was limited to sending a command instructing a selected cellular device to register with the CMR system in response to a telephone call. In contrast to the discrete page processing conducted by prior cellular devices, the present invention uses one or more pages carried by the cellular network control channel to form a command and/or data sequence for use by a controller coupled to the receiving device. The invention is particularly useful for communicating and programming schedule information for the control operations of a PLC coupled to the cellular-compatible device.
The present invention is preferably implemented for use with a data message system that adapts an existing architecture and communications protocols for a conventional CMR system to supply an advantageous approach to the communication of data collected from one or more remote sites. In this data message system, which is described in U.S. Pat. Nos. 5,546,444, 5,526,401 and 5,873,043, a cellular communications device can send a data message to a mobile switching center (MSC) via the cellular network control channel. In addition, the MSC can send commands and/or data in the form of pages to one or more cellular communications devices via the cellular network control channel. U.S. Pat. Nos. 5,546,444, 5,526,401 and 5,873,043 are assigned to the assignee of the present application and are hereby fully incorporated herein by reference.
It will be understood that the communication of messages between the MSC and a cellular communications device can be conducted by adapting conventional techniques and known protocols of a CMR system for data communications. Accordingly, prior to describing the detailed operation of the data message system, it will be useful to review the operation of a typical CMR system.
A CMR system is generally characterized by dividing a radio coverage area into smaller coverage areas or “cells” using low power transmitters and coverage-restricted receivers. As will be known to those skilled in the art, the limited coverage area allows the radio channels used in one cell to be reused in another cell. As a mobile radiotelephone within one cell moves across the boundary of the cell and into an adjacent cell, control circuitry associated with the cells detects that the signal strength of the mobile radiotelephone in the just-entered cell is stronger, and communications with the mobile radiotelephone are handed-off to the just-entered cell.
A CMR system typically uses a pair of radio frequencies for each radio channel and each cell. Each cell typically includes at least one signaling channel, also referred to as a cellular network control channel or an access channel, and several voice channels. The control channel is selected or dedicated to receive requests for service from mobiles and portables, to page selected mobiles or portables, and to instruct the mobiles or portables to tune to a predetermined voice channel where a conversation may take place. Accordingly, the control channel is normally responsible for receiving and transmitting data to control the communication actions of the mobile and portable radiotelephones.
The control channel normally comprises a FOCC for communications from the MSC to a radiotelephone unit and a reverse overhead control channel (RECC) for communications from a radiotelephone unit to the MSC. The FOCC supplies a multiplexed data stream of message data words, a busy idle signal, and busy idle bits. The busy idle bits are useful for supplying an indication to monitoring radiotelephones about the current status of the RECC. If the RECC is in use by a radiotelephone unit, then the RECC is considered to be busy and the busy idle bit is set to a binary one value. Alternatively, if the RECC is not in use, then the RECC is considered to be idle and the busy idle bit is set to binary zero value. Mobile radiotelephones monitor the busy idle bits transmitted by the FOCC and, if the busy idle bit is set to a binary one value, then the mobile radiotelephone delays transmission on the RECC until the busy idle bit is set to a binary zero value. Thus, a radiotelephone normally transmits on the control channel during the window of opportunity that is presented by a transition from the busy state to the idle state. In particular, the busy idle bit supplies an instantaneous view of the signaling activity on the control channel, and the conventional radiotelephone is responsive to this instant snapshot of control channel activity.
The data message and radio channel specifications for U.S. cellular radiotelephone systems are set forth in Electronic Industries Association/Telecommunications Industry Association (EIA/TIA) Standard 553, implemented in accordance with 47 C.F.R. § 22, in the Report and Orders pertaining to Federal Communications Commission (FCC) Docket No. 79-318. Copies of the EIA/TIA-553 may be obtained from the Engineering Department of the Electronic Industries Association at 2001 Pennsylvania Avenue, N.W., Washington, D.C., USA 20006.
It is known that when a cellular mobile radiotelephone originates a call, it transmits a series of data messages to the serving cell. These messages, commonly referred to as Call Origination, are defined by EIA/TIA-553. These data messages contain the low order seven digits of the unit's telephone number, known as the Mobile Identification Number (MIN), the unit's Station Class Mark (SCM), which identifies functional characteristics of the unit, and the Called Address, or dialed telephone number. Cellular system operators typically also require additional data words to be transmitted that contain the MIN2, which is the high order three digits or NPA of the cellular unit's telephone number, and the Electronic Serial Number (ESN). The MIN is assigned to a particular radiotelephone unit by the cellular service provider selected by the subscriber. The MIN typically contains information unique to the CMR system operator, for example, the first three digits of the MIN (“XXX”) typically correspond to an area code, the next three digits (“XXX”) typically correspond to a geographic location within the area code; and the final four digits (“XXXX”) identify a particular piece of equipment. Similarly, the ESN is unique to each mobile cellular radiotelephone unit, and comprises a format that allows differentiation as to manufacturer and; in some cases, the model number, date of manufacture, and the like.
These messages are provided first to the cell, and then through a data link to a mobile telephone switching center, otherwise described as a mobile switching center. The MSC, also known as a MTSO or a “switch,” makes voice connections between mobile radiotelephones and other telecommunications networks. At the MSC, a determination is typically made whether the radiotelephone is an authorized user or subscriber by looking up the unit's telephone number, serial number, and other information supplied by the radiotelephone to see if there is an entry in the MSC's database corresponding to that particular telephone. An optional function of an MSC is to validate that the ESN and MIN received as part of a Call Origination message are valid. If the MIN is valid and the radiotelephone is identified as a subscriber within the given cellular system, i.e., a “home” unit, the received ESN is compared to the MSC's database ESN entry to detect fraud. If these checks succeed, the cellular call is then allowed to proceed.
It is also well known that when a mobile radiotelephone first powers up or first enters a CMR system when already powered, the unit can identify itself as actively present within the system. The radiotelephone identifies itself or “registers” through a process known as Autonomous Registration by supplying a data packet similar to that of a Call Origination message. The Autonomous Registration signal, also referred to as a registration or identification signal, typically comprises data fields for at least a mobile telephone number, i.e., the MIN, and an ESN. The original design attempt of Autonomous Registration was to improve the efficiency of potential future call deliveries by keeping the MSC informed of the approximate whereabouts of each individual radiotelephone unit, and to reduce paging channel load by lessening the need to page all cells to find a particular cellular unit. When the MSC is thus informed, it can later “page” or attempt to ring the cellular unit only in the cell or area that it was last known to be in. Additional cells would be paged only if the initial page did not locate the particular radiotelephone. Thus, Autonomous Registration is simply a set of messages periodically and autonomously sent from the mobile radiotelephone to the serving cell at an interval specified in data parameters previously received from the cell by the cellular unit.
Referring now to the drawings, in which like numerals indicate like elements throughout the various figures,
The data message system 10 adapts the existing environment of a CMR system to communicate data from one or more remote sites to a central location. However, to conserve the use of voice channels of the CMR system for conventional telephone conversations, the data message system 10 uses the cellular network control channel of the CMR system for data communications. This permits conservation of the valuable frequency spectrum dedicated to the voice channels of the typical CMR system.
A typical CMR system includes a geographic radio service area, such as indicated by the cell 12, of which a plurality of cells are typically provided in a typical cellular service operator's system. The cell 12 is served by a broadcast antenna 14 to permit communications between cellular mobile radiotelephones operating within the cell 12 and a cell control 16. A mobile telephone switching office, such as the MSC 24, can communicate with the cell 12 either by dedicated telephone facilities (not shown) or, more frequently, by a cell-to-mobile switching center data link 22 between the cell control 16 and the MSC 24. At least a portion of the data link 22 is typically supported by a wireless communications link, such as the microwave link 20, located between the cell 12 and the MSC 24.
It is well known to those skilled in the art that the conventional CMR system comprises at least one mobile telephone switch coupled to an appropriate array of more or less identically equipped cell sites 12. The MSC 24 normally couples telephone conversations involving mobile radiotelephones operating in the cell 12 to the public switched telephone network (PSTN) 26 through telephone facilities 28. The data message system 10 includes a set of data reporting devices 29, each comprising at least one controller 32′ and a cellular communications device 34. A cellular communications device 34 can communicate with the MSC 24 via a control channel of the CMR system. The controller 32′, which is connected to one or more instruments or controllable items via a signal path 31′, is typically implemented as a PLC for controlling the operations of a field instrument or a controllable item. The cellular communications device 34, which is connected to the controller 32′ via a signal path 33′, can communicate with the MSC 24 via a cellular network control channel 38 and accept page messages containing commands and/or data for use by the controller 32′. In addition, the cellular communications device 34 can transmit data messages, typically formatted as a Call Origination message or an Autonomous Registration signal, to the MSC 24 via the cellular network control channel 38.
In the alternative, the data reporting device 29 can include a monitor 32, shown in
The MSC 24 can communicate with the cellular communication devices 34 via the cellular network control channel 38, which is formed by the combination of the data link 22 and a cellular communications link 36 between the broadcast antenna 14 and the cellular communications device 34. This combination of communications links is collectively referred to as the control channel. It is well known that a cellular network control channel for a conventional CMR system comprises two radio channels that are commonly described as a FOCC 38a and a RECC 38b. The FOCC 38a is used for communications initiated by the MSC to a radiotelephone unit, such as the cellular communications device 34. In contrast, the RECC 38b is used for communications from a radiotelephone unit to the MSC 24. The communications operations of the data message system also use this convention for communications between the MSC 24 and the cellular communications device 34. In particular, the control channel 38 comprises two separate data communications paths, an FOCC 38a for communications initiated by the MSC 24 and an RECC 38b for communications initiated by the cellular communications devices 34 (or mobile radiotelephones operating within the cell). Accordingly, the cellular communications device 34 transmits data messages via the RECC 38b, whereas the MSC 24 transmits page messages, typically comprising commands and/or data, via the FOCC 38a.
In this manner, the MSC 24 can transmit command and data to each of the cellular communication devices operating within the coverage areas of an array of cells for the CMR system 8. Likewise, the MSC 24 can receive data messages from each of those cellular communications devices 34. Although the data messages contain selected data rather than the parameters normally contained in an actual radiotelephone control information, the MSC 24 will operate upon the data messages as if they were transmitted by a conventional radiotelephone operating within the cell because the data messages are formatted to appear as a registration signal or a call origination signal generated by a radiotelephone unit.
The MSC 24, in response to a data message transmitted by a data reporting device, can conduct one or more of the following operations: store the data message for processing at a later date, process the selected data supplied by the data message, or forward the data message to a data collection system 40 via a first communications link 42. The data collection system 40, which is connected to a memory storage device 44, collects the selected data by storing the received data messages within the memory storage device 44. Similar to the MSC 24, the data collection system 40 also can process the selected data to obtain further information concerning the operation or performance of the data sources 30. Alternatively, the data collection system 40 sends the data message to a data processing system 46 via a second communications link 48. The data processing system 46 is typically remotely located from the data collection system 40 and facilitates convenient processing of the selected data at a central site. The second communications link 48 is typically implemented by a conventional telephone facility, a dedicated data link, or by a wireless communications link.
Referring still to
The remote cellular system identified by the data message is not an actual operating cellular system for supporting telephone conversations, but rather is dedicated to data collection applications and is represented by the data collection system 40. In recognition that the cellular communications device 34 is actually associated with the remote cellular system, the MSC 24 forwards the data message to the data collection system 40 via the first communications link 42. The data collection system 40 responds by sending to the MSC 24 a message which confirms that the roamer associated with the data message is a valid or authorized user of the remote cellular system. The cellular communications device 34 is thereafter added as a registered radiotelephone to a database of registered roamers at the MSC 24.
The data collection system 40 has now received the data message containing selected data. Accordingly, the data collection system 40 transmits a message to the MSC 24 that instructs the MSC to delete the cellular communications device 34 from its list of registered roamers. It will be understood that the MSC 24 would normally receive this type of message when a roaming radiotelephone has moved to another cellular system and subsequently registered for operation on that other system. Thus, the database of the MSC 24 is no longer required to maintain the registration information concerning the cellular communications device 34 after transferring the data message to the data collection system 40.
Alternatively, the MSC 24 clears its database of such registration information upon the expiration of a certain time interval. The data collections system 40 can respond to the data message by transmitting a message which confirms that the roamer is a valid user and further instructs the MSC 24 to delete the registration entry upon the expiration of the certain time interval. As a separate option, the MSC 24 can automatically delete a registration entry from the MSC database upon expiration of a certain time period without any instruction from the data collection system 40. In this manner, the data collection system 40 is not required to send yet another message to the MSC 24 after the data collection system 40 confirms that the cellular communications device 34 represents a valid user.
The MSC 24 and the data collection system 40 are preferably compatible with the EIA/TIA Interim Standard 41 (IS-41 standard). The IS-41 standard defines a communications protocol for communications between two cellular systems. The IS-41 standard allows cellular calls to be handed-off between dissimilar cellular systems, not unlike the way that calls are handed-off between cells of a single CMR system. In addition, the IS-41 standard permits call deliveries and a communications exchange for verifying whether a cellular caller is a valid cellular service subscriber. In this manner, the MSC 24 hands-off or forwards the data message to the data collection system 40 via the first communications link 42, which is preferably implemented as an IS-41-compatible network. In response, the data collection system sends a user validation message via the link 42 to confirm that the source of the data message, specifically a cellular communications device 34, is a valid cellular source.
In particular, the data collection system 40 recognizes that the received data message contains selected data which has been transmitted by a cellular communications device 34. Accordingly, the data collection system 40 processes the received data message and compares the predetermined identifying characteristic in its data message to a list of such characteristics in its database. This database preferably contains an entry of the predetermined identifying characteristic for each of the known cellular communications devices 34 and corresponding data that identifies the associated device as a valid cellular source. Upon obtaining a positive match, the data collection system 40 preferably responds to the received data message by sending to the MSC 24 the verification message. It will be appreciated that the data collection system 40 also can forward to the MSC 24 a message confirming the absence of a valid entry for the cellular communications device 34 in response to a negative match.
This validation message can also include a profile of communications services that are authorized for use by the particular cellular source. For example, this user profile typically defines the operations limitations for the cellular source, including access to long distance services, the capability for the source to only originate (and not receive) calls via the cellular system, etc. The user profile information can contain an instruction that commands the MSC 24 to delete from its database the registration entry for the particular cellular communications device after the expiration of a certain time period. This allows the MSC 24 to clear from its database entries for cellular communications devices 34 that have communicated their data message via the cellular system 8 by registering with the MSC 24 because such devices no longer require the continued communications support of the MSC 24.
The data collection system 40 can store the selected data supplied by the received data message within the memory storage device 44, can process the selected data and store the resultant data, or can forward the selected data to the data processing system 46 for processing. Prior to sending the selected data to the data processing system 46, the data collection system 40 first converts the data message to an acceptable communications protocol for conveying the data message to the data processing system 46. This step is necessary prior to communication with the data processing system 46 because, unlike the MSC 24 and the data collection system 40, neither the data processing system 46 nor the second communications link 48 are compatible with the IS-41 standard.
Although the MSC 24 is typically programmed to treat the cellular communications devices 34 as roamers associated with a foreign cellular system, it will be appreciated that the database of the MSC 24 also can be programmed to contain entries for the predetermined identifying characteristics of those cellular communications devices 34 operating within the cells of the cellular system 8. Upon receiving a data message via the control channel 38 from such a device 34, an MSC 24 containing such database entries will identify the transmitting cellular communications device 34 as a “home” unit rather than as a roamer because the MSC database contains an entry that corresponds to the predetermined identifying characteristic supplied by the message. Thus, the MSC 24 registers the transmitting cellular communications device 34 as a home unit of the cellular system 8. This avoids the additional requirement of contacting a foreign cellular system, such as the data collection system 40, to inquire whether this cellular source is a valid user or subscriber of cellular services.
However, to, initiate the necessary transfer of the information in the data message to the data collection system 40, the MSC 24 for this embodiment is adapted to recognize that data messages should still be forwarded to the data collection system 40. Specifically, based upon a portion of the predetermined identifying characteristic that is uniquely associated with the data collection system 40, the MSC 24 locates an entry in its database that commands the switch to send all messages containing such a characteristic to the data collection system 40. Accordingly, the MSC 24 thereafter forwards the data message via the first communications link 42 to the data collection system 40.
The data collection system 40 can be implemented by a computer. One embodiment for the data collection system 40 is the computer of a service circuit node. Certain manufacturers of switches, such as the MSC 24, also offer devices for implementing communications with the data collection system 40, including the Motorola EMX switch and other vendor proprietary switches. The cellular system 8 is preferably implemented as an AMPS or a DAMPS cellular system. However, it will be appreciated that the cellular system 8 also can be compatible with alternative cellular systems, such as the GSM system, implementing a control channel for mobile-to-cell communications.
It will be appreciated that the CMR system 8 includes an array of cells, such as the cell 12, and that a set of reporting systems 29, each formed by the monitor 32 and the cellular communications device 34, are typically located in a cell. For each data source 30 within the cell 12, the monitor 32 (controller 32′) and the cellular communications device 34 are preferably located proximate to the data source 30 (instrument 30′) to minimize the lengths of the signal paths. To facilitate economical installation of the reporting device, the monitor 32 (the controller 32′) and the cellular communications device 34 can be combined within the same housing and this housing can be installed either adjacent to or as an integral part of the data source 30 (instrument 30′). For an installation proximate to the data source 30 or a controllable instrument 30′, the signal paths are preferably formed by hard-wired connections between the connected devices. Nevertheless, it will be appreciated that the signal paths also can be implemented as either infrared communications links or wireless communications links.
The data collection system 40 can be located proximate to or as an integral part of the MSC 24, in which case the first communication link 42 preferably forms a hard-wired connection between the devices. However, the data collection system 40 also can be positioned at a remote site. For this remote installation, the first communications link 42 can be implemented as a wireless communications system, such as a microwave system, or as a dedicated data line, such as a conventional telephone facility. For the convenience of the party that is sponsoring the collection of a particular type of data, the data processing system 46 is typically located at another remote site that is typically proximate to the sponsoring party.
By using the data message format associated with an Autonomous Registration signal, the cellular communications device 34 “registers” with the MSC 24 by sending a data message that appears to contain a mobile telephone number and an ESN. Although it is not intended for the cellular communications device 34 to place a conventional voiced-based cellular telephone call, the cellular communications device 34 nevertheless registers for operation with the MSC 24, thereby enabling the communication of the selected data from the field.
Alternatively, the format for the data message can be identical to the format or data record for a Call Origination signal that is transmitted by a cellular radiotelephone when it originates a telephone call. Similar to the format for a registration signal, the cellular communications device 34 can appear to originate a call by sending a data message formatted as a Call Origination signal to the MSC 24. Although the MSC 24 processes the data message as if it contained a mobile telephone number and an ESN, the data message is actually used to communicate selected data placed within one or more data fills normally reserved for the mobile telephone number and the ESN. Although the Call Origination signal format can be used to transport data from the cellular communications device to the MSC, it will be understood that the data message system 10 is employing this format for data communication rather than for call origination.
As shown in the data record 50 in
Furthermore, the data field 54 in the data message for remote data corresponds to the location within the data record for the ESN. Those skilled in the art will appreciate that the ESN is 32 bits long and includes 8 bits for a manufacturer code. For cellular systems that do not review or screen ESNs based upon the manufacturer code segment, it is possible to manipulate the data field normally filled by an ESN to supply a data message having a data field 54 containing 32 bits of selected data. However, if the cellular system uses the manufacturer code segment of the ESN, the selected data within the data field 54 comprises a length defined by the remaining 24 bits of the ESN. For most applications, it will not be necessary to manipulate the manufacturer's code segment of the ESN because a data message having 24 bits of selected data (and, as required, 8 bits of the manufacturer code segment for a conventional ESN) should be sufficient to supply relevant data.
It will be appreciated that the signal path 31 represents one or more signal channels for transferring the selected data to the recorder 60 and, furthermore, that the recorder 60 can be implemented as either a single or multi-channel recording device. Each signal channel normally would be associated with a different operating or performance characteristic for the data source 30.
For certain applications, the recorder 60 records selected data from the data source 30 for a predetermined time period. A clock 66 connected to the recorder 60 supplies timing data to the recorder 60, thereby enabling the recorder 60 to add a time tag to the selected data. The time tag indicates the relative time for the start of each predetermined time period of recording operations. Assuming that the predetermined time period is a known value, the addition of the time tag data permits the calculation of the start and completion times for each data reporting operation. Correlation of the data collection time to the selected data is desirable for certain processing operations. The clock 66 can be implemented as a conventional counter supplied by a hardware device or as a software routine executed by a microprocessor.
The cellular communications device 34 includes at least a data receiver 70, a cellular transmitter 72, and a controller 74. The data receiver 70, which is connected to the recorder 60 via the signal path 33, receives the selected data obtained from the data source 30 by the monitor 32. The controller 74, which is connected to the data receiver 70 and the cellular transmitter 72, controls the respective operations of the data receiver 70 and the cellular transmitter 72. The controller 74 is preferably a microprocessor-based control system that can be programmed to conduct control operations in a manner known to the art.
In response to the selected data, the controller 74 prepares a data packet containing the predetermined identifying characteristic associated with the cellular transmitter 72 and the selected data collected from the data source 30. The cellular transmitter 72 responds to the data packet by transmitting a corresponding data message via the control channel 38 of the CMR system 8. Specifically, the cellular transmitter 72 uses the RECC of the control channel 38 to send data messages to the MSC 24. Although the cellular transmitter 72 can be implemented as a conventional transmitter for a radiotelephone unit, the preferred cellular transmitter 72 uses only the data radio channels of the CMR system 8 for transmission of data messages.
The cellular communications device 34 further includes a memory storage device 76 connected via a bi-directional data path to the controller 74. The selected data received by the data receiver 70 can be stored in the memory storage device 76 prior to the transmission of a data message by the cellular transmitter 72. Although the memory storage device 76 is shown as a separate memory from the memory storage device 62, it will be appreciated that the memory storage devices 62 and 76 can be implemented as a single memory which is accessible by both the recorder 60 and the controller 74. The memory storage device 76 can include one or more masks, as shown in
To connect the cellular communications device to another device, such as a monitor 32, a signal path is connected between both devices, as illustrated by signal path 33 in
To receive communications from the MSC 24 via the FOCC of the cellular network control channel 38, the cellular communications device 34 also includes a cellular receiver 78. The cellular receiver 78, which is connected to the controller 74, can be implemented as the cellular receiver for a conventional radiotelephone. However, similar to the cellular transmitter 72, the preferred cellular receiver 78 operates to receive information primarily via the data radio channels rather than the voice radio channels of the CMR system.
The cellular transmitter 78 typically transmits the data message only when the control channel is available for clear use by the cellular communications device 34. This form of data queuing minimizes the possibility that the operation of numerous cellular communications devices 34 within the cell 12 will interfere with normal telephone conversations involving the operating radiotelephones within the cell. Nevertheless, it will be appreciated that the cellular transmitter 78 also can transmit the data message without first checking the availability of the control channel 38.
Alternatively, the cellular communications device 34 can be programmed to transmit the data message during a certain time interval, such as during the early morning hours between midnight and 6 AM, when control signal traffic is normally at a minimal level. To permit this type of automated transmission operation, the cellular communications device 34 includes a clock 82 connected to the controller 74. The clock 82 outputs a clock signal in response to expiration of a time interval. In response to the clock signal, the controller 74 initiates a data message transmission by the cellular transmitter 72. In this manner, selected data is transmitted during a known time interval from one of the reporting devices within the cell 12 to a central location.
The clock 82 preferably outputs the clock signal during the time period when use of the control channel 38 is at a reduced level, thereby minimizing the possibility that the cellular communications device 34 will interfere with the normal communications operations of the CMR system 8. In particular, the time interval is preferably selected with advance knowledge of the reduced activity periods for conventional telephone conversation traffic on the CMR system 8 to ensure that data message transmissions by the various cellular communications devices 34 in the cell 12 are conducted on a noninterference basis with voice call processing messages transmitted to and from the radiotelephones operating in the cell. The clock 82 can be implemented as either a hardware counter or as a software counter implemented by coded instructions executed by the controller 74.
A data transmission by the cellular communications device 34 also can be initiated in response to a status signal output via the signal path 33 by the monitor 32. This status signal causes the cellular communications device 34 to transmit the stored selected data via the RECC of the control channel 38. The monitor 32 typically outputs the status signal in response to the completion of a data recording event. For example, in a typical vending equipment application, the monitor 32 can output the status signal in response to an alarm event, such as the detection of a maintenance service requirement. Alternatively, for an utility load management application, the monitor 32 can output the status signal in response to detection of possible tampering of the utility's load control device. Those skilled in the art will appreciate that the generation of the status signal is event-driven and that the applications for the data message system 10 will determine those events.
It will be appreciated that the process of outputting a clock signal or a status signal to initiate a data message transmission by the cellular communications device 34 is similar to an Autonomous Registration operation that is conducted by certain known radiotelephone units. For an Autonomous Registration, the radiotelephone automatically identifies itself to the cellular system by initiating its own registration operation. Likewise, for the described embodiments, the cellular communications device 34 responds to the clock signal or the status signal by sending a data message having a message format that is representative of the data record for a registration signal (Call Origination signal) of a radiotelephone unit. In turn, the MSC 24 receives the data message via the control channel 38 and subsequently operates upon the data message as if it were a registration signal (call origination signal) transmitted by a conventional radiotelephone unit.
It is well recognized that a cellular network control channel, such as the control channel 38, is a two-way communications path between the MSC 24 and the radiotelephone devices operating in the cell 12. Specifically, an MSC 24 can send a paging message or “page” to one or more radiotelephone devices operating within the coverage area defined by the cell 12 of the CMR system 8. In contrast to conventional radiopaging systems, this page message is transmitted via the FOCC of the CMR system rather than via a radiopaging terminal. For CMR systems, this page message is typically used to notify a cellular mobile radiotelephone device that an incoming telephone call is pending, thereby prompting the cellular device to register with the CMR system.
The receiver 78 can receive pages from the MSC 24 via the FOCC of the control channel 38. For example, the MSC 24 can output command signals, which are formatted as pages, via the control channel 38 to initiate certain operations or to control certain functions of one or more of the cellular communications devices 34 within the cell 12. The receiver 78 can monitor the control channel 38 for finite time periods defined by a clock signal output by the clock 82. For example, the clock 82 can operate as a timer defining a time period for a monitoring operation completed by the receiver 78. The cellular communications device 34 can respond to a command signal by conducting a particular operation or by controlling a certain function associated with the command signal.
The command signals typically include address data and each cellular communications device 34 responds to a command signal containing its predetermined address data. This allows the MSC 24 to communicate with one or more of certain cellular communications devices 34. By proper use of the addressing operation, it is possible for the MSC 24 to remotely control the operations or functions of a subset of the cellular communications devices 34 that is selected from the overall group of devices 34 within the cell 12.
The command signal is preferably a 10 digit number that represents a conventional mobile telephone number. At least a portion of this telephone number can be assigned as an identifier for a corresponding cellular communications device 34. The remaining portion (if any) of the 10-digit telephone number can represent a command or data for a particular operation or function. In this manner, a cellular communications device 34 can be programmed to respond only to a command signal containing its address data and to conduct the particular operation or function identified by the command.
By transmitting command signals to the cellular communications devices 34, the MSC 24 can remotely control various operations of the cellular communications devices 34 or can remotely define various programmable operating parameters of the devices 34. For example, in response to a selected command signal, the cellular communications device 34 “registers” with the MSC 24 by transmitting a data message to the MSC 24. It will be appreciated that this command signal is similar to a conventional Locate Request signal generated by a CMR system, such as the AT&T Autoplex System, and requests registration of a selected radiotelephone unit. By use of this command signal, a selected cellular communications device 34 can be polled at any time by the MSC 24 to initiate the transmission of a data message containing the desired selected data.
For another representative example, the time interval for the clock 82 can be modified or otherwise replaced with a substitute time period in response to a command signal. The cellular communications device 34 also can instruct the monitor 32 to initiate a recording of data from the remote data source 30 in response to yet another command signal. In particular, the controller 74 responds to the detection of the command signal by the cellular receiver 78 and outputs an instruction signal to the recorder 60 to prompt the data reporting operation.
The opportunity for placing a command or data, or a combination of a command and data, within the conventional format of a paging message is limited by the defined character length of the paging message, typically the 10-digit telephone number or MIN. For relatively short data lengths, the transmission of a single independent page message from an MSC to a cellular device in the manner known to the art is useful to support limited communications. This fixed data length for a page message is satisfactory for the paging communication task of conventional CMR system operations, namely, the polling of one or more mobile radiotelephones within the coverage area of the CMR system. This polling technique only requires the transmission of a single discrete page message to prompt a response from a mobile radiotelephone unit that receives the page. Prior to the present invention, there was no readily available mechanism for exploiting the paging message mechanism to transfer an expanded data set.
As described in U.S. Pat. No. 5,873,043, a data message system can be constructed to communicate multiple page messages or pages via the cellular network control channel to a cellular-compatible receiving device. The data obtained from each received page can be combined to form an aggregate message comprising a data sequence. An exemplary data reporting system 29 can be constructed to support the transfer of commands and/or data via pages carried via the FOCC for use by a controller, such as a programmable logic controller device. Turning now to
An exemplary format for a page message capable of communicating a command and/or data to a cellular communications device is described in U.S. Pat. No. 5,873,043. For an exemplary embodiment of the data message system 10, it will be appreciated that command and/or data digits can be encoded within a series of pages transmitted by the MSC 24 over the FOCC. For example, the Least Significant Digit (LSD) of a MIN in a page can be used to indicate an associated action to take on the FOCC DATA. This format requires a 1K block of MINs, for example, 0XX-100-0000 to 0XX-100-0999. Five decimal digits of data can be encoded into two data pages. Each of the data digits are encoded according to Table 1, below, which is zero-based right to left, but stored in the FOCC page left to right.
Table 2 describes the relationship between the LSB of a MIN and the digits of FOCC DATA, including the function corresponding to that data.
In decision step 506, an inquiry is conducted to determine whether the cellular communications device has received a target page with a specific identifier matching one assigned to the device. If the response to this inquiry is positive, the “YES” branch is followed to step 508. A negative response to this inquiry results in the process following the “NO” branch from step 506 to step 518.
In step 508, a determination is made whether a prime timer at the cellular communications device is active. If the prime timer is not active, the “NO” branch is followed to step 510 and the timer is activated. Otherwise, the “YES” branch is followed from step 508 to step 512 and the prime timer is stopped. For the exemplary process 500, the prime timer completes a timing operation for a period of 60 seconds upon activation unless interrupted during that time period. For example, the prime timer can be interrupted in step 512 in response to receiving a second target page within the time period of the prime timer. In contrast, the prime timer will be activated in step 510 in response to receipt by the cellular communications device of a first target page in a sequence of a pair of target pages.
In step 514, a separate timer, the ARM timer, is started and a predetermined time period, typically 60 seconds, is begun. In step 516, the process returns to the START step 502 to initiate continued monitoring operations by the cellular communications device.
If a target page is not received in step 506, an inquiry is conducted in decision step 518 to determine whether the cellular communications device has received a data page. If the response to this inquiry is negative, the “NO” branch is followed from step 518 to step 504 to continue monitoring operations. Otherwise, the “YES” branch is followed from decision step 518 to step 520. A determination is made in step 520 whether the ARM timer is active. If so, the cellular communications device has received a pair of target pages, each having a matching identifier, during the time period of the prime timer. The process proceeds to step 522 based upon a positive response to the inquiry in step 520. If, on the other hand, the ARM timer is not active, the process returns to step 504 to continue monitoring operations by the cellular communications device.
If the ARM timer is active, the cellular communications device is monitoring the FOCC for one or more data messages transmitted by the MSC of the CMR system. In step 522, a determination is made whether the received page represents a first data page in a sequence of data pages to be received by the cellular communications device. For the exemplary process, the first data page is designated by the placement of a 0, 1, 2, or 3 in the minimum LSD of the MIN structure of the page message. If the received page is the first data message, the “YES” branch is followed from step 522 to step 524 to process the first data message. Otherwise, the “NO” branch is followed from step 522 to step 526.
In step 526, a determination is made whether the received page represents a second data page in a sequence of pages received by the cellular communications device within a time period. For the exemplary process, the second data page in a sequence of a pair of pages is designated by the placement of a 4 or 5 in the minimum LSD of the MIN structure of the page message. If the response to this inquiry in step 526 is positive, the “YES” branch is followed to step 528 to initiate processing of the second data page. Otherwise, the “NO” branch is followed from step 526 to step 530.
In step 558, the cellular communications device can send an acknowledgement signal to confirm receipt of the data carried by the received data pages. The acknowledgement signal is preferably formatted as an Autonomous Registration signal in the form of AAAAdddd. An Acknowledge Pattern is represented by “AAAA (hex)”, whereas received data is represented by the “dddd” pattern. The cellular communications device sends the acknowledgement signal via the RECC to the MSC of the CMR system.
In step 560, the received data is processed by the cellular communications device. This data processing task can include forwarding the data from the received pages to a controller, such as a PLC, to program control operations for completion by that device. The cellular communications device typically forwards the received data via a wired or wireless communications link to the controller. In turn, the controller can store the programming data within a look-up table maintained in its memory. For example, the received data can designate a slot or entry in the look-up table and programming data for storage within that look-up table slot. In step 562, the process returns to the START step 502 in
Returning now to
If the response to the inquiry conducted in decision step 530 is negative, the process proceeds to the EXIT step 534. As shown in
As shown in
Upon receipt of a target page to its Primary (slot 0) MIN or Group 1 MIN (slot 1), the target radio 34 will start a prime timer having the predetermined time period, such as a 60 second timer. If the prime timer expires prior to a subsequent target page carrying the same MIN, the target radio 34 will execute a default function. If a second target page arrives prior to the prime timer's expiration, however, the target radio 34 activates an ARM timer having a predetermined time period, such as 60 seconds, and awaits receipt of the first data message, i.e., a page carrying data content. If that message is received via the FOCC prior to timer expiration, it will reset the ARM timer and continue to reset until all data is received. If at any time the ARM timer expires, then the target radio 34 will return to normal operation. All non-armed radios will ignore the data pages. The MSC will only simultaneously transmit one data sequence per MSCID to avoid target radio confusion.
The two data pages, called FOCC data messages, convey decimal digits of data via the FOCC to the now-armed target radio. If both FOCC data messages are correctly received, the target radio 34 preferably sends to the MSC 24 an Autonomous Registration signal with the upper 12 bits containing the Acknowledge Pattern “AAA (hex)”. The lower 20 bits are the received data represented in BCD in big-endian order.
If a single FOCC data message is used (LSD of 6, 7), and this data page is correctly received, the target radio 34 will send an Autonomous Registration signal with the upper 24 bits containing the Acknowledge Pattern “AAAAAA (hex)”. The lower 8 bits are the received data represented in BCD in big-endian order.
Table 3 describes a representative example for the communication of a target MIN and data content via a sequence of pages to a cellular communications device via the MSC. For this example, the assigned block of MINS are “009-100-0000 to 009-100-099.” The memory of cellular communication devices responsive to target MINS within this assigned block have a memory mask set to “009-100-0aaa,” where ‘a’ indicates a “wildcard” of zero through nine. In other words, the cellular communication devices representing the family of target radios have a memory mask set to “0090100-0aaaa, wherein the least four significant digits of the mask can be any number from zero through nine. To communicate the 5-digit data set of “47109” to a target radio, the page sequence defined in Table 3 is communicated as data pages by the MSC via the FOCC.
First, a target page having a target MIN assigned to the desired set of cellular communications devices 34 or target radios are transmitted by the MSC 24 via the FOCC within a 60 second period. For example, the MSC can send the target page having the MIN of “009-100-0999 to prompt an action by these target radios. Each activated target radio will now monitor the FOCC for one or more pages containing data content, also described as an data pages. For the example described in Table 3, the data content of “47109” is transmitted by the MSC as a pair of data pages, using either a default “even” MIN structure or a default “odd” MIN structure. For the even MIN structure, the first data page comprises “009-100-0900” to communicate the data content “09” and the second data page comprises “009-100-0174”. In turn, the target radio can acknowledge receipt of this data content by sending an Autonomous Registration signal with the upper 12 bits comprising the Acknowledge Pattern of “AAA” (hex) and the lower 20 bits representing the received data content of “47109”.
Table 4 describes another representative example for the communication of a target MIN and data content via a sequence of pages to a cellular communications device via the MSC. In contrast to the example shown in Table 3, however, the data content is transmitted by the MSC 24 to each target radio 34 in the form of a single data page “009-100-0586” for an even default MIN or “001-100-0587” for an odd default MIN.”
Commands and data can be transmitted by the MSC 24 via the cellular network control channel 38 to cellular communications devices 34 coupled to controllers 32′, such a programmable logic controllers (PLCs). A controller 32′, also described as a PLC, can be programmed by sending the programming content from the MSC 24 to the cellular communications device 34 coupled to that controller. In turn, the cellular communications device 34 can forward the received programming to the controller 32′. For controller applications, an inventive data protocol can be used to support the performance of control tasks relative to a pre-defined schedule of events. Examples of applications that are able to use such a protocol include, but are not limited to, irrigation systems, gate controls, entry systems, lighting controls, etc.
For a representative weekly schedule application, each PLC can be programmed in memory based on a 100-entry look-up table to minimize the amount of weekly paging required for a given unit. Each entry (slot) in the look-up table can be stored in a memory location of the PLC at the time of manufacture or prior to installation for the specific control application. In the alternative, the look-up table programming can be communicated to the PLC by sending a programming entry to the corresponding cellular communications device. A typical schedule for a control application is a one-week schedule. An example of a look-up table for a single use facility, based on 5 schedules (00–04) and 24-hour time (0000–2400 hours), is shown below in Table 5. The schedule shown in Table 5 can be preprogrammed into a PLC during the start-up phase of the controllable system.
An example of a representative page message structure for a schedule command is shown in Table 6.
This exemplary schedule command page has the MIN format of 080-100-CNNA, where the MIN suffix CNNA is a 4-digit representation of the combination of the command MIN designator (C), the look-up table slot number (NN) and the schedule command (A). The “080-100” portion of the MIN has been set aside or reserved for use in connection with weekly schedule paging applications.
The paging of a unit for each week can comprise the representative paging sequence shown in Table 7.
The first page serves as a target page having the default MIN or target MIN to alert the desired target radios to monitor the FOCC for schedule programming information in the form of another page, typically a schedule command page. If a target radio having the MIN mask corresponding to the default MIN “080-101-5151” receives a page having that MIN, then the target radio will start to monitor the FOCC for a page carrying the schedule MIN. The schedule command page carries the data content of “1039”, which designates the page as a command page, defines the appropriate slot in the programming look-up table, and identifies the standard schedule.
Once the target radio has received both the target page and the schedule command page, the target radio issues an Autonomous Registration signal serving as an acknowledgment of the command receipt. This acknowledgement comprises the form “AAAAAANN” for at least 64 seconds after the target page has been received. The “AAAAAA” field represents an Acknowledgment Pattern, whereas the “NN” field represents the looking table slot number. If the registration acknowledgment is not received, then the page sequence can be reissued for a predetermined number of times, typically up to two more times by the MSC.
In decision step 615, an inquiry is conducted to determine whether the cellular communications device has received a target page having a specific identifier assigned to that device. If the response to this inquiry is negative, the “NO” branch is followed from step 615 to step 610. The receipt of a target page by the cellular communications device can transition the focus of monitoring operations from target pages to schedule command pages. In an alternative embodiment, the receipt of a pair of target pages within a predetermined time period will result in the transition of this monitoring operation from target pages to schedule command pages. In either embodiment, the reception of target page(s) having a matching identifier results in a transition of the focus of monitoring operations completed by the device.
In decision step 620, an inquiry is conducted to determine whether a schedule command page has been received within a predetermined time period by the cellular communications device. A negative response to this inquiry results in the process looping back to step 610 to continue monitoring operations. On the other hand, a positive response results in the process proceeding from decision step 620 via the “YES” branch to step 625.
In step 625, the cellular communications device extracts a schedule command from the schedule command page and forwards that command to a controller, such as a PLC coupled to the device. The data content of the scheduled command typically defines a slot for entry in a programming look-up table maintained in memory by the PLC. The look-up table includes multiple slots or entries, each stored in a memory location and containing programming data defining control operations for the PLC.
In step 630, the PLC retrieves a programming command from the look-up table slot identified by the schedule command page to initiate programming operations by the PLC.
In step 635, the cellular communications device can send an acknowledgement signal via the cellular network control channel. The acknowledgment signal is typically formatted as an Autonomous Registration signal having a ESN field with the form “AAAAAANN.” The cellular communications device transmits the acknowledgment signal via the RECC to the MSC to confirm receipt of the schedule command page.
An exemplary process for reprogramming the slots in the schedule look-up table of a PLC can be based on a communication by an MSC of a paging sequence over the FOCC to a cellular communications device coupled to the PLC. For a weekly schedule application involving a PLC having 8 controllable relays, the total number of permutations for the combination of 256 relay state possibilities, 288, 5-minute time segments in a 24-hour day, and a 7 day/week schedule is 516096. Consequently, an exemplary format for the programming data stream is SSPPPPPP, where “SS” is the slot number and “PPPPPP” is the permutation number. The data sent to the target radio comprises a slot number and a permutation number. This results in a total of four command pages and a page for the Default MIN. After every two command pages, the target radio preferably acknowledges receipt of the schedule commands with a Autonomous Registration signal having an ESN of the format “AAAAdddd”. For this ESN format, “AAAA” signifies that this message is a page acknowledgment (an Acknowledgment Pattern) and “ddd” represents the data elements of the received pages.
The digits in a schedule command page can be used in accordance with the information shown in Table 8.
As shown in Table 9, to reprogram the slots in the schedule look-up table of a PLC, an exemplary communication process is completed based on a paging sequence communicated over the FOCC between the MSC and a cellular communications device coupled to the PLC.
An example of a paging sequence for reprogramming communications is shown in Table 10:
For the representative example of a sequence of pages described in Tables 9 and 10, the first page represents the target page having a default MIN to alert particular target radios having the corresponding MIN mask that commands and/or data will be communicated via the FOCC for use by those target radios. The representative example of this default MIN page is “080-100-5151,” which designates an odd default MIN. The schedule slot number of “89” is defined by the second page of “080-100-1891.” The least significant digit of “1” designates this page as the first page of look-up table programming. The third page of this paging sequence, “080-100-1503” defines the 2 most significant digits of the permutation, “50,” and includes the least significant digit of “3” to designate this page as the second page of look-up table programming. In response to this page sequence, the target radio issues an acknowledgement signal in the form of an Autonomous Registration signal “AAAA8950,” which contains the slot number “89” and the 2 most significant digits of the permutation “50.”
In response to the acknowledgement signal, the MSC issues the fourth page of this paging sequence, “080-100-1385,” which defines the next 2 most significant digits of the permutation, “38,” and includes the least significant digit of “5” to designate this page as the third page of look-up table programming. In turn, the MSC transmits the fifth and final page of the paging sequence, “080-100-1627, which defines the 2 least significant digits of the permutation, “62,” and includes the least significant digit of “7” to designate this page as the fourth page of look-up table programming. In response to this page sequence, the target radio issues an acknowledgement signal in the form of Autonomous Registration signal “AAAA3962,” which contains the next 2 significant permutation digits “39” and the 2 least significant permutation digits “62.”
If a programming change occurs locally, typically by the end user or a field technician, in a schedule look-up table, then the target radio can issue a registration sequence to the MSC. In turn, the MSC can forward this information to the data collection system as an update for the schedule information maintained at an Operations Center responsible for schedules.
In decision step 720, a determination is made whether the cellular communications device has received a schedule command page having a schedule table slot number and a schedule command page having programming data. If the response to this inquiry is negative, the “NO” branch is followed from step 720 to step 710 to continue monitoring operations. If, on the other hand, the cellular communications device has received both schedule command pages within a predetermined time period, the “YES” branch is followed from step 720 to step 725.
In step 725, the cellular communications device extracts the schedule table slot number and the programming data from the pair of scheduled command pages and forwards this information to the PLC coupled to the device. In turn, the cellular communications device can send an acknowledgement signal via the cellular network control channel in step 730. The acknowledgement signal is typically formatted as an Autonomous Registration signal for communication via the RECC to the MSC of the CMR system.
In decision step 735, a determination is made whether the cellular communications device has received additional scheduled command pages containing data during a predetermined time period. If the response to this inquiry is negative, the “NO” branch is followed from step 735 to step 710 to continue monitoring operations at the cellular communications device. If, on the other hand, the cellular communications device has received additional schedule command pages in a timely fashion, the “YES” branch is followed to step 740. For an exemplary embodiment, programming data is typically carried by this pair of additional scheduled command pages. The programming data carried by the additional scheduled command pages is extracted by the cellular communications device and forwarded to the PLC in step 740. This programming data can be combined with the slot number and programming data received by the PLC in step 725 to support a reprogramming operation at the PLC. For example, the combination of programming data can be stored by a look-up table at the slot number identified by a received scheduled command page to update or to reprogram the programming data at that look-up table slot.
In step 745, the cellular communications device can send an acknowledgement signal via the cellular network control channel to acknowledge receipt of the additional schedule command pages. The cellular communications device typically transmits the acknowledgement signal as an Autonomous Registration signal via the RECC to the MSC of the CMR system.
For a representative PLC, there exists 8 preprogrammed Modes, or Relay States. An exemplary example of the page structure for an On/Off override command MIN is shown in Table 11.
The paging sequence for the On/Off Override Command typically comprises a target page having the default MIN followed by the command page. Once a target radio has received both pages, it issues an Autonomous Registration signal of the format AAAAAAAA at least 64 seconds after reception of the default MIN. If this acknowledgment signal is not received by the MSC via the FOCC within a certain time period, then the MSC reissues the page sequence.
In step 820, a determination is made whether the cellular communications device has received a command page carrying an ON/OFF override command via the cellular network control channel. If the cellular communications device has not received the command page, the “NO” branch is followed from step 820 to step 810 to continue monitoring operations. If, on the other hand, the cellular communications device has received a command page with an ON/OFF override command during a predetermined time period, the process follows the “YES” branch from step 820 to step 825. The cellular communications device forwards the ON/OFF override command in step 825 to the PLC coupled to the device. The PLC can store the ON/OFF override command within memory, such as the programming look-up table.
In step 830, the cellular communications device transmits an acknowledgement signal via the cellular network control channel to acknowledge receipt of the command page carrying the ON/OFF override command. The acknowledgment signal is preferably formatted as an Autonomous Registration signal carried by the RECC for receipt by the MSC of the CMR system.
In a representative example of a PLC device, there exists 10 preprogrammed responses to data requests. An example of the structure for data request command page is shown below in Table 12.
The paging sequence for the Data Request Command consists of the target page carrying the default MIN followed by the data request page. Once the target radio has received both pages, it can issue an Autonomous Registration signal carrying the requested data in the form of a data message. If the registration signal is not received within a certain time period of the MSC, then the page sequence can be reissued by the MSC.
In normal operation, when the target radio issues an alarm, the alarm message comprises an Autonomous Registration signal transmittal via the RECC. This alarm message can be followed by an Autonomous Registration signal carrying specific information related to that alarm. Regular status registrations are preferably accomplished by a single registration formatted as an Autonomous Registration signal.
In step 920, a determination is made whether the cellular communications device has received a data request page carrying a data request command via the cellular network control channel. If the cellular communications device has not received the data request page, the “NO” branch is followed from step 920 to step 910 to continue monitoring operations. If, on the other hand, the cellular communications device has received a data request page with a data request command during a predetermined time period, the process follows the “YES” branch from step 920 to 925. The cellular communications device forwards the data request command in step 925 to the PLC coupled to the device. The PLC can respond to the data request command by forwarding the requested data to the cellular communications device in step 930. In turn, the cellular communications device can issue in step 935 an Autonomous Registration signal formatted as a data message carrying the requested data. For the exemplary embodiment, the requested data is typically a preprogrammed response stored in memory of the PLC and associated with the particular data request.
A representative projection of the monthly traffic loading for a CMR system using the process controller scheduling protocol described above in Tables 5–12 is illustrated below in Table 13.
It should be understood that the particular embodiments described herein have been disclosed by way of example and that other modifications may occur to those skilled in the art without departing from the spirit of the inventive concept.
The present application claims priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application Ser. No. 60/154,724, filed on Sep. 20, 1999, fully incorporated herein by reference, and is related to U.S. patent application Ser. No. 08/212,039, filed on Mar. 11, 1994, now issued as U.S. Pat. No. 5,546,444, to U.S. patent application Ser. No. 08/331,794, filed on Oct. 31, 1994, now issued as U.S. Pat. No. 5,526,401, and to U.S. patent application Ser. No. 08/769,142, filed on Dec. 18, 1996, now issued as U.S. Pat. No. 5,873,043. The present application is a continuation of and claims priority to U.S. application entitled System for Communicating Messages Via a Forward Overhead Control Channel For a Programmable Logic Control Device, filed Sep. 20, 2000, having Ser. No. 09/666,042 now U.S. Pat. No. 6,718,177.
| Number | Name | Date | Kind |
|---|---|---|---|
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| Number | Date | Country | |
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| 20040157597 A1 | Aug 2004 | US |
| Number | Date | Country | |
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| Number | Date | Country | |
|---|---|---|---|
| Parent | 09666042 | Sep 2000 | US |
| Child | 10770326 | US |
