Patent Application
20050206505
The present invention relates generally to remote message display and communication devices. More particularly, the present invention relates to digital communication, control, and display devices for annunciator systems.
Existing annunciator lamp technology, including devices known in the art as dome lights, and further including those for medical applications, uses multiple wires from each served examination or patient room to light multiple lamps within a dome light at a location outside the door of the patient room. There may, in some applications, be one wire per lamp with a common return. This affords moderate complexity at each room, since there are likely to be four or more informational signals that can be sent from each room plus an emergency signal.
Each in-room controller in a typical prior-art system may feature a transmitting control station with a switch and a confirming light on the control station for each signal. There may further be a pull cord activating a switch for an emergency signal. Each switch closure may send power from a power supply to a corresponding lamp on the dome light assembly, then to a common return. It is understood that a similar system with two dedicated wires per switch closure could also be implemented, at further cost in wiring complexity.
Such an annunciator system may be highly reliable, but may represent a significant cost in installation materials and labor as well as complexity.
Annunciator systems in a variety of configurations are employed for rapid communication, often in spatially extended environments. Communication may be limited to a single device originating messages that are received and presented by a network of receiving devices, may involve multiple devices sending messages to a central information management station, or may involve bidirectional communication, either between a center and multiple peripherals or between multiple stations.
Annunciators may include visual (lights, text messages, icons, etc.), aural (tones, recorded spoken words, etc.), and tactile (vibration generators, etc.) indications as appropriate for an application. Computer hardware and software may be included in an otherwise noncomputational system as appropriate.
“Medical Staff Management” (MSM) or “Call for Assistance” (CFA) annunciation devices are typically wired directly to a centralized annunciation panel (CAP) located at a hospital nurse's call station or at the front desk in a doctor's office, for example. The primary purpose to which a CAP is put is alerting medical staff to a specific condition, situation, or status in a remote location such as a medical examining room. A typical condition may be a patient requiring assistance or a particular room requiring service, for example.
Current CAP technology requires labor-intensive installation and generally consumes relatively large amounts of basic materials. In particular, from each room, power and/or control wires generally must be routed to the CAP. This makes the system bulky and difficult to maintain or upgrade.
Many CAP products indicate conditions, status, or information by lighting incandescent lamps. The drawback to such lamps is that they commonly burn out after a limited working life. Therefore, a CAP may require frequent maintenance and may experience failures of individual functions.
In applications for which a need for more detailed annunciation is established after initial installation, a typical system requires physical expansion to accommodate additional wiring and added bulbs. For example, in a standard hospital application, a single white bulb, such as a common miniature incandescent lamp covered by a colorless lens, may be a sole annunciation used to alert medical staff personnel that a patient requires attention. Although such a lamp can announce an immediate need, the lamp furnishes no detail regarding the type of assistance needed. Further, in the case of an MSM application, that is, an environment such as a doctor's office, each patient typically receives a sequence of services. Here, the single lamp provides a front desk organization with no detail regarding service status. Such detail could indicate what action or service is next required in a room. For example, a patient may require a special service or may have already been seen by a nurse and be ready for a physician or physician's assistant. Requests of these types may not be adequately conveyable using a single lamp, or even a single color, on a CAP. Multiple lamp colors, which may be desirable to encourage efficient resource flow, may not be practical, as when the number of lamps is small compared to the amount of information to be transferred.
Annunciator systems can further be subject to obsolescence, so that an initially adequate system may show significant shortcomings later. For example, a prior-art annunciator system may use one or two wires from each switch in a room to a corresponding lamp in the CAP. If such a system, even a system with more than one indicator per room, requires another indication function per room, then still more wires as well as new switches may be required. For example, two lamps and an emergency (pull cord, or lanyard) signal per room for a ten-room facility might require sixty wires feeding into a CAP, plus provision for in-the-wall AC power distribution to the satellite station in each room. Pre-installing extra wires may be feasible to save follow-on labor, but may typically add to initial cost without guaranteeing future benefit.
Accordingly, it is desirable to provide an annunciator system apparatus and method whereby a multiplicity of indications is available from a series of patient services rooms to a central administration station. It is further desirable that such an apparatus and method require a minimal-complexity wiring system to support a minimal annunciator system, while permitting subsequent functional extension without installation of additional wires or upgrading of central administration station apparatus.
The foregoing needs are met, to a great extent, by the present invention, wherein in one aspect an apparatus is provided that in some embodiments provides an annunciator system apparatus and method with multiple signals and information-rich displays. An annunciator system according to a preferred embodiment of the invention also provides a multiplicity of communication link options that can use a minimal wiring configuration to carry a large and expandable flow of information.
In accordance with one embodiment of the present invention, a monitor system is presented. The monitor system comprises a master controller, a satellite controller distal to the master controller, a bused communications interconnect that links the master controller and the satellite controller, and a message protocol configured to transmit data over the bused communications interconnect.
In accordance with another embodiment of the present invention, a monitor system is presented. The monitor system comprises means for polling a satellite controller with a master controller over a common bused communication medium. The bused communication medium is configured to be linked to a plurality of satellite controllers. The monitor system further comprises means for transmitting a response from the satellite controller in response to the polling, and means for determining a status of the satellite controller based upon the response.
In accordance with yet another embodiment of the present invention, a method for monitoring status of a multiplicity of medical services rooms from a single remote site is presented. The method comprises polling a satellite controller with a master controller over a common bused communication medium, wherein the bused communication medium is configured to be linked to a plurality of satellite controllers, transmitting a response from the satellite controller in response to the polling, and determining a status of the satellite controller based upon the response.
There have thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described, and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be used as a basis for the designing of other structures, methods, and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
Established annunciator technology for environments such as doctors' offices, clinics, and primary care facilities may have provisions for identifying the status of individual patient rooms, such as by the presence of file folders in a basket outside the door. More technologically elaborate solutions may include, for example, a single lamp outside a patient room controlled by a switch inside the room. All such basic solutions have limited utility and none provides emergency support. More elaborate lamp-based indicator systems, to include those with two or more lamps in a dome light assembly, can include complex control wiring, possibly requiring one or more wires per lamp. Such systems may lack the ability to support enhancements without altering or adding wiring.
An exemplary embodiment of the present invention may include at least one lamp in a dome light assembly that can be affixed outside a patient's room in a medical clinic, for example, which dome light assembly can be controlled from a control station inside the same room. The dome light assembly may receive both power and control signals on a single wire pair from the control station. It may be desirable for the single wire pair that provides power and control to be implemented using multiplexed control signals, contained, for example, in a serial digital command string. This is particularly true for feature-rich dome light assemblies. Some such assemblies can include more than one lamp. In some, the individual display elements within the dome light can be provided with filters, different color light emitting diodes (LEDs), or equivalent features to permit emission in different colors. In some, the lamp can emit using heightened-alert features such as flashing. In some, the dome light assembly can include capability for emitting sound.
It should be noted that terms such as controller, processor, microprocessor, personal computer, and the like are used substantially interchangeably herein, with qualifying terms added to indicate functional and location distinctions. A digital electronic device that can read and write data from and to external and/or internal device interfaces and storage, and which executes a predetermined or modifiable instruction sequence that may include making decisions based on input data or events may be assigned any of a multiplicity of names, but be substantially interchangeable in practice. A typical controller device may include internal analog-to-digital conversion (ADC) capability, internal instruction and data storage, and ability to access external communication devices, for example. Another controller device may have no internal storage and no internal ADC but instead have built-in communications functions, for example, yet be essentially equally suitable for embodiments of the inventive apparatus and method described herein.
Turning now to the figures, wherein like elements are denoted by like reference numerals throughout,
Power to the control station 14 may originate in utility wiring 22, from which it may be fed from a central transformer 24 by low-voltage alternating-current wiring 26 serving preferably a multiplicity of control stations 14, 28 and 30 through power distribution wiring 32. Shielding 34 on all power distribution wiring 32 may likewise be desirable.
The control station 40 in the preferred embodiment, shown in greater detail in
An internal face of the control station 40 also is shown in
A control station 40 may be powered, for example, from bused, intrinsically safe power, such as the 24-volt transformer-isolated alternating-current power supplied from a central power supply 24 and distributed by low-voltage wiring 26 as shown in
Input signals to a microprocessor 102 configured as a receiver (jumper 104 set high by a jumper between pins 1 and 2 thereof) may arrive on an input line 116, which line can be pulled low by a weak resistor 118 and permitted to swing high during positive-going signals by a coupling capacitor 120. Output signals from a microprocessor 102 configured as a transmitter (jumper 104 set low by a jumper between pins 2 and 3 thereof) can be configured to drive bipolar transistors 122 and 124 to force output line 126 high during each logic-1 interval, which intervals are determined by the internal processing of the transmitter microprocessor 102 and output from pin 4, named RA2, thereof. Output line 126 is pulled low by load current in the receiver microprocessor circuit driven by the transmitter-configured circuit, including quiescent current in the regulator IC of the dome light assembly and current drawn by any lamps illuminated in the control station 40 panel and the dome light assembly 80.
The signal timing indicated in the exemplary embodiment, shown in
Once the start bit 132 has established timing, successive samples can be taken at the center of each successive bit time. In the exemplary waveform, which transmits the least significant bit (LSB) 142 first, only Bit 3148 is active. This could correspond to a doctor call lamp being steadily lit, for example. Similarly, setting Bit 4150 could correspond to an emergency, Bit 5152 to activation of the sound generator, Bit 6154 to flash all active lights, and Bit 7156 to flash sequentially instead of simultaneously any lights enabled to flash by Bit 6154.
Other message formats are possible, such as the use of a longer command word, which command word could include assignment of more than the previously mentioned two bits, thereby providing for more state options for each lamp. Another option, transmitting, for example, a single message per lamp, could include a lamp number and a command code. Another option could leave the transmitter with the burden of keeping track of display functions, and could require the transmitter to send a new command word for each state change in the dome light. Thus, to emulate the above operation, a flashing doctor call would require a new command to be sent each half-second —first on, then, after a half-second wait, off-instead of sending a flashing-doctor-call command once.
Other electronic line drivers and receivers and their associated microprocessor ICs may be usable in place of the devices shown in
Fiber optic communication may also be feasible, although the properties commonly viewed as making fiber desirable may be of limited benefit in the exemplary system. For example, fibers can be used to transmit the commands described above, and have the particular advantage of being effectively free of risk of causing interference in other medical apparatus in a room. Such approaches typically require separate power connections. Using another approach, light from high-brightness signal sources such as laser diodes, sent through low-loss fibers used as light pipes, can directly illuminate diffusers, so that neither electrical power nor active parts are required at the dome light unit.
Applications of the present invention can include support of multiple-station ward areas with multiple entrance doors. For such configurations, central timekeeping—that is, a single master clock to which all stations would be resynchronized periodically—may be preferable. Such synchronization, with microprocessor IC 102 transmitters programmed to start their respective transmissions only at specific intervals, may require bit transmit times to be uniform after a button is pressed at any station. Using the open-collector configuration of the output transistor 124 in
In a preferred embodiment, the present invention provides a master controller located at a central station, a satellite controller located in each of a multiplicity of remote rooms, a communications interconnection system such as a wiring network, a power distribution provision, and a communications signal protocol. Each master controller and each satellite controller includes a stored-program processor, along with volatile and nonvolatile memory for use with the controller and for data storage.
In the preferred embodiment, the satellite controllers are controlled by one or more sensor inputs, where such sensors may be implemented with electromechanical circuit closures such as isolated switches, coincidence of row-and-column activation as in a keypad matrix, detection of a physical property such as a capacitance change or surface-acoustical-wave reverberation due to finger pressure on a touch sensor, voice recognition, or other embodiment. The master controller detects electronic signals sent by the satellite controllers according to the protocol, and causes actuation of one or more indicators such as lamps, icons, and/or text messages to be displayed in response to the signals received. Indicator devices, including display elements, audible signals, and other functions of the master controller, may be controlled in part by the content of the signals from the satellite controllers, in part by control inputs located at the master controller, and in part from commands transmitted from a central controller to which the master controller reports.
In the preferred embodiment, the satellite controller 212 and a master controller 234 which is located at a medical staff management station 236 are interconnected for example by wiring such as shielded cables 238. The wiring system in the preferred embodiment can be made up from any number of wired connections, such as an impedance-controlled twisted pair multi-drop bus, addressed in more detail below.
It may be observed that the panel 250 shown is one of many types possible. The 3-line text display 252 presents data in one of many possible formats. Discrete pushbutton switches 254 and LED indicator lamps 258 are preferably included in the embodiment. An alternate embodiment can represent the entire display panel 250 of
The schematic diagram 260 of
The IC driver 264 for the sounder 280 may in some embodiments be a self-contained fixed tone generator. In other embodiments, a tone generator may store one or more downloaded tone waveforms that it then reproduces. In still other embodiments, the tone generator may amplify a tone injected into it, which tone in such embodiments might be created within the processor 262 from a lookup table, might be calculated from a mathematical model in software, or might be a recording or a voice message from another device, for example. For any tone generation method, of which the aforementioned are examples, the output in the embodiment shown is fed to the front panel interface connector 276. Assembling the master controller 246 connects the sounder 280 to the front panel interface connector 276. In still other embodiments, the sounder 280 may be mounted on the master controller 246 circuit board, with a grille or other port on the front panel serving to pass the sound to the outside.
The selection of an IC driver device 266 for the front panel visual display is determined by the details of the front panel display in each embodiment. For example, an embodiment could use incandescent lamps to show status of each remote station 212, in which case a lamp-compatible driver IC 266 with a separate output port for each lamp could be preferred. In another embodiment, light-emitting diodes could be used as direct replacements for incandescent lamps, in which case a LED-compatible driver IC 266 using an organization similar to that of the incandescent-compatible driver might be preferred. In still another embodiment, where a liquid crystal display is used as the display device 274, yet another display interface IC 266 could be required, in addition to which a backlight power supply (not shown) could be needed. Still other display devices 274 are self-contained, that is, they include storage registers for display data. For compatibility with such displays, a digital data interface, possibly including external buffers, could suffice in lieu of power drivers. A circuit board layout compatible with multiple display styles may be preferable.
Communication between patients'rooms (216 in
An example of a communications protocol that can use such a communications arrangement is Electronic Industry Association (EIA) Recommended Standard (RS)-485. RS-485 is intended to use a differential signal and is compatible with using a single master controller 234 and a multiplicity of satellite controllers 212 sharing a single bused wire pair. RS-485 calls for all satellite controllers 212 to wait until polled, so the limit on system size is largely determined by the data rate chosen, the message length, and the desired system refresh rate. For example, if a polling system has an assigned bit rate of 19.2 Kbps, a system refresh rate of ½ second, a quantity of satellite controllers 212 in the system limited to 32, and incoming and outgoing messages of equal length, then a message length of about 150 bits (more than 18 bytes) is possible.
The preferred embodiment also shows an Ethernet® port 270, which may be used for communication between a master controller 260 and a supervisory computer (not shown), may be used to permit groups of satellite controllers 212 to be clustered, or may be used in lieu of the RS-485 bus. It may be observed that typical applications of Ethernet use from two to four twisted pairs of wires throughout a system, as well as using a switching device that includes a dedicated multiple pair cable per Ethernet port. While a hardware-intensive approach of this kind may be less desirable in general, the materials for an Ethernet-based configuration are in common use, and thus may be preferable for some applications. Ethernet may also allow a high data rate, which may have additional benefits.
In some embodiments, an individual master 260 may support a floor or a wing of a hospital, for example, as one of multiple masters 234 reporting to a central office of the hospital. Communication between the multiple masters 234 and the central office, which may preferably use an Ethernet configuration, may be polled, or, according to system architecture preference, may use asynchronous message transmission by each of the masters 260.
Use of a switch closure detection IC 272 may be preferable in order to enhance system robustness. However, in a system 210 with good noise protection, such as one with a processor IC 262 featuring high intrinsic immunity to static discharge or with a housing that readily dissipates charge and is grounded, a separate switch closure detection IC 272 may be redundant.
A bidirectional communications connector 268 may serve a single shielded pair in the case of a system with one RS-485 link only, or may support more than one RS-485 and/or Ethernet or another communication protocol, as preferred. RS-485 and similar protocols may likewise be implemented using nonshielded wire pairs, coaxial lines, and other electrical interconnect technologies, as well as fiber optic data lines.
A front panel interface connector 276 requires enough connections to support the display method selected for an embodiment, as well as to support as many switch closures as may be required for an embodiment. The connection technology chosen for an embodiment, for example pin-in-socket, ribbon-in-slot, ball grid array, or another, may be a matter of individual preference. Human interface event detection may use individual switches, crosspoint switch matrices, polling, or other methods. Sound and other functions may be supported on the board or through the front panel interface connector 276. Alternative embodiments may avoid using a separate connector by various technical alternatives, such as direct wiring of a cable to the circuit board, direct mounting of display and switch closure devices on the circuit board, and the like. In some such embodiments, some or all passive devices (resistors, capacitors, etc.) and active devices (ICs and other semiconductor devices) may preferably be mounted on a back surface of the circuit board.
Use of a power connector 278 may be preferable for many master controller 260 embodiments. Power may be fed directly from premises wiring (nominally 120 volts AC in the U.S. and some other countries, 240 volts AC in most others) to a circuit board, may be isolated and/or reduced in voltage with an external transformer (242 in
Interconnection technologies other than implementation of RS-485 using a shielded twisted pair bus may likewise be preferred for other embodiments, such as embodiments for use in applications wherein a user has a comparable but possibly incompatible wiring system already in place. In such applications, a system upgrade method capable of reusing existing wires may be preferable. A preexisting system with unshielded direct wiring from each patient's room back to a master station, for example, may be reconfigurable as parallel pairs branching out from the master with acceptable noise and speed performance.
Wireless and pseudo-wireless systems may be preferred in alternate embodiments. Typical “true” wireless systems may employ bidirectional radios similar to those used in wireless Ethernet, described in Institute of Electrical and Electronics Engineers (IEEE) standard 802.11. Pseudo-wireless systems may couple radio-frequency AC signals into and out of premises electrical power distribution wiring within a facility. In applications in which such are strategies realistic, wireless interconnection may be preferable.
Housing for a preferred embodiment of the inventive apparatus 210 described herein may be one of a desktop enclosure, a flush mount style wall panel, a surface mount style wall panel, a rack mount style enclosure, and any other workable combination of electronic device enclosure, visual display, multiple switch closure interface, electrical power interface, and wiring interconnection. An acoustic emitter and/or detector, such as a speaker and/or a microphone, may be desirable elements within each such configuration.
The preferred embodiment, through use of a bused interconnect 238, achieves a low wire count, in exchange for which the wiring functions as a comparatively effective transmission line.
Polling is a method whereby a central functional unit (master controller 234 in
The preferred poll/response embodiment disclosed herein will be referred to as master/satellite. The satellite controllers 212 may preferably be configured to respond only when the master controller 234 polls them.
The master controller 234 can preferably include a microprocessor 262 that can detect valid addresses from satellite controllers 212 and associated apparatus, representing, for example, patient rooms 214 on an RS-485 network, and can configure an internal active mapping that can then be stored in flash ROM that is external or internal to the master controller microprocessor 262.
Flash ROM is an electronic storage medium that can retain data such as the above mapping indefinitely without a source of external power until flash ROM content is reconfigured by a user. By using flash ROM, satellite controllers 212 may be added immediately or later in order to accommodate system expansion. Flash ROM also permits a previous configuration to be retained despite repeated removal and application of power.
Satellite controller addresses are ordinarily assigned to satellite controllers 212 in individual rooms, although additional addressable controllers in a network may function as security and safety interfaces, hallway speakers, pagers, and other devices that are not room satellite controllers 212.
A network in a preferred embodiment can support up to 32 satellite controller addresses, which corresponds to the transmitting load limit of a system designed to conform to the baseline specification for RS-485. More addresses—rooms and other facilities—an be added beyond 32 by a variety of methods, including the addition of one or more RS-485 repeaters. An RS-485 repeater may be a bidirectional signal booster that occupies one unit load, which would require that a primary-network device be deleted from a fully-compliant RS-485 based network for every added repeater. In that case, a fully loaded system with a master and three repeaters in a star configuration (a first string of satellite controllers 212 in any branching arrangement of twisted pair wires with impedance adjusting terminations at branch points, and with three of the satellites omitted in favor of repeaters, each of which drives its own fanout of 32 satellites) could support as many as 32×3+(32−3)=125 rooms or equivalent loads. Variations on RS-485 can also accept more satellite controllers 212 per master controller 234, for example by increasing line impedance and lowering the load current each satellite controller 212 is allowed to draw.
The master controller 234 in the preferred embodiment is configured to poll each room, detecting any status changes that may have occurred since the last polling. Status changes will normally correspond to switch activations in a patient's room that have not been responded to previously. The master controller 234 may preferably compare the last recorded status to the current message content for each room. If the two differ, the master controller can update its room status register and activate the appropriate lamp/LED/LCD display element to match the room's status. If no active status is reported, the master controller can deactivate the lamp/LED/LCD display element for the polled room.
It may be observed that, in a typical MSM or CFA system, the likelihood of a switch activation event in any polling period may be relatively low. As a result, a system in which satellite controllers 212 record and report switch activation and release events and so inform the master controller 234 during each polling cycle may follow up such satellite controller 212 reports during a first polling period by having the master controller 234 asynchronously send an acknowledgement that allows a state machine within the satellite controller 212 to advance from a “sensed but not yet acknowledged” state to a “sensed and acknowledged” state. In the latter state, the satellite controller 212 can activate a local indicator corresponding to the switch activation or release, can return to a quiescent state, or can respond in another appropriate way. For example, if push buttons and indicator lights are present on the satellite control panel, then pressing a specific push button, even momentarily, can set a pair of data elements within the satellite controller 212, one recording the button press and the other the release. During the next polling event, the satellite controller 212 can report the button push, or, if the system is so configured, both events. Either immediately or after completing the polling sequence, the master controller 234 can command the satellite controller 212 to turn on the associated indicator light ( 226 or 228 in
When a lanyard switch 244 is activated in a patient's room, the master controller may illuminate the “emergency” status and override any current status for the respective room. An “emergency” status may preferably be assigned the highest priority of all status indicator types. The master controller 234 may have the capability to activate a sounder (280 in
For a preferred master controller embodiment, a message containing 11 bytes and limited to ASCII characters may be employed. It is to be understood that alternative message formats may be preferred in some embodiments. The following is a description of the poll message:
A typical polling-based operational scheme compatible with a preferred embodiment of the invention could take the form of a data request message with the form—
<STX><U><A><F1><F2><F3><F4><F5><ETX><ck1><ck2>
. . . where <STX> is a single byte start-of-text message, <U><A> is a two byte unit address (00-FF), while <F1>, <F2>, <F3>, <F4>, and <F5> is single byte data fields, <ETX> is a single byte end-of-text field, and <ck1> and <ck2> is a two byte checksum.
Regarding timing for this example, bit time at 19.2 Kbits/sec is just over 52 microseconds per bit. With 11 bytes transmitted from the master controller 234, the total transmission time is roughly ((11 bytes ×8 bits/byte)×52 microseconds per bit =4.58 msec. Response time of the satellite controller 212 is likewise 4.58 msec because it also contains 11 bytes. Total time for a poll and response is 4.58 msec×2=9.16 msec. For an entire 32 unit network, then, 32×9.16 msec=293 msec. At this speed, satellite controller 212 switch closures can be detected with a high level of reliability. If a retry is attempted on the next poll, the response time doubles (293 msec×2=586 msec). This provides a repetition rate faster than one polling cycle per second.
As an example, a master controller polling a room could send out the following message having a series of ASCII characters to a room in which a satellite controller 212 that has been assigned the address 02 is located:
<STX>02 4 3 0 0 0<ETX>5C
In the above example, the master controller polling address is 02, the F1 and F2 fields contain the command 43, which has been designated as the poll command, and fields F3, F4, and F5 are padded with zeroes as they are not needed in the poll command. The message terminates with <ETX> and is then followed by a two-byte block checksum.
In this example, the block checksum is calculated to be 5C as follows. Each byte is converted to its hexadecimal value, after which a summation proceeds, starting at the <U> byte and ending with the <ETX> character. <STX> has a hexadecimal weight of 02h and the <ETX> character has a weight of 03h. Dropping the high byte in the resultant leaves the lower two bytes, with a value of 5C (hex).
When the target satellite controller 212 receives the poll message, it calculates the block checksum and compares it to what was sent from the master controller 234. If the two checksum values match, the message is presumed to be error free and ready for processing. However, if the checksums differ, the satellite controller 212 can transmit a <NAK> character, for example, to indicate that a corrupt message was received. In response, the master controller 234 can retry the transmission, for example up to a set number of times. If the message continues to arrive corrupted, the master controller 234 can post a communications fault indication on its network. The fault indication can show which satellite controller 212 address appears to be experiencing trouble. The master controller 234 panel trouble display and sound generator 280 can be set to annunciate. A provision for muting the sound generator 280 after acknowledgement can be included in system design.
This is a typical method for generating a robust checksum for raising data transmission confidence. Other methods can provide lesser or greater levels of confidence, such as parity bits that provide rudimentary verification, data encryption routines that can identify many specific single and multiple bit faults in short messages and can allow some troubleshooting of a data path, and error correcting codes that can in some configurations allow operation in an electrically noisy environment.
The following 11 byte message can be a satellite controller's response to the polling message above:
<STX>02 4 3 0 1 0<ETX>5D
The <STX> <U> <A> <4> <3> can be an echo what was received by the satellite controller 212. The F3, F4, and F5 fields can be populated with the unit's current status. See Table A for a typical status indication field description.
The decoding and verification process for the returned message may be essentially symmetrical with that for the polling message. Checksum errors in a returned message may result in the master controller's retransmission of a data request message.
System initialization after application of power may include a configuration check in which the master controller transmits every possible address, requesting switch status of each address. Barring failures, an exhaustive search may be expected to detect that all of the addresses previously in use (and stored in flash ROM) respond with an indication that no switches are activated. Many system malfunctions may be detected in this way, since depowered or misprogrammed satellite controllers 212 may fail to respond or may respond incorrectly, and stuck switches, or their equivalents in satellite controllers implemented without mechanical switch devices, can be expected to show up as active switches where none such are expected. Such a test can also be activated by selection from a functional menu if implementation of such features in a particular embodiment is desired.
In the case where the message is parsed 306 and received successfully 308, the room switch status is read out of the message 318. If there is no activity, the loop is repeated for the next room. In the case where there is room activity 318, the room number and switch status details are extracted from the message 320. If the activity is Emergency Pull Cord 322, then the sounder and emergency lamp are activated 324, after which normal loopback resumes and the next room is polled 304. If the activity is not Emergency Pull Cord, then the energization status of the appropriate panel indicator is changed 326 and the next room is polled 304.
It may be observed that the flow chart described provides a summary of normal operation of the system. This routine 300 proceeds continuously, while additional support processes, such as checksum generation and analysis, new satellite controller 212 activation, and the like operate according to schedules or by interrupt as required.
It may be further observed that the status of a patient room is available outside the room. A further application of positionally and color coded multiple-state information allows indicators in a corridor to be activated to allow staff to note status without requiring a return to a central station. The instant invention can support this efficiency enhancement by maintaining continuous supervision of equipment condition and by providing emergency monitoring, which can allow staff to reduce unnecessary detours.
Sufficient bandwidth may be available in some embodiments to permit two-way voice communication between a master controller 234 and a satellite controller 212. This may be implemented in many ways, such as by including a microphone at each of the controllers and digitizing detected sounds. A series of signal samples taken at a sufficiently high data rate (on the order of 2000 samples per second, for example) and transmitted using coder/decoder (CODEC) technology or another signal management process, can adequately reconstruct voice sent using a digital transmission line. Playback may require decoding at approximately the original sampling rate. Bidirectional, nearly real-time conversation can be managed between a master controller 234 and a satellite controller 212 along with management of all other satellite controllers 212 on a network, if the system bit rate is calculated to accommodate the required data rates. A similar function can be used to allow the master controller to broadcast announcements to a selected group of satellite controllers 212.
Although an example of the master controller 260 is shown using a dedicated microprocessor 262 with internal flash ROM for program and data storage, as well as RAM for volatile data storage, it will be appreciated that a general purpose microcomputer, such as a personal computer, which may have a fixed disk as the basis for both its operating system and any needed volatile data backup storage, and which may further employ dynamic RAM for active program and data storage, may be preferred. Also, although the master 234 and satellite 212 controllers herein described may be useful in a doctor's office to help in the management of services provided to patients in multiple examining rooms, they may also be suited for use in hospitals, convalescent homes, rapid medical response facilities, medical laboratories, and other medical-related facilities, as well as in hotels, schools, cruise ships, subway trains, sports clubs, and other public accommodations wherein central coordination facilities support multiple separate facilities with multiple functions per facility.
The many features and advantages of the invention are apparent from the detailed specification, and, thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to that fall within the scope of the invention.
This application claims priority to and is a continuation-in-part of U.S. patent application entitled TWO-WIRE DOME LIGHT POWER AND CONTROL SYSTEM, having a Ser. No. 10/802,916, now pending, the disclosure of which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10802916 | Mar 2004 | US |
| Child | 10901229 | Jul 2004 | US |
