Can bus router for building automation systems

Abstract

Systems and methods for implementing CAN bus routers in building automation systems are disclosed. An exemplary system may comprise a control area network (CAN) backbone. At least one CAN router may be connected in-line to the CAN backbone. A plurality of automation devices may be connected to the at least one CAN router for communication over the CAN backbone.

Description

TECHNICAL FIELD

The described subject matter relates to building automation, and more particularly to Control Area Network (CAN) bus router for building automation systems.

BACKGROUND

The ability to control one or more devices in a building (e.g., lighting, heating, air conditioning, security systems) based on one or more parameters (e.g., time, temperature, user preference) is known as building automation. Building automation may be implemented in any of a number of different types of buildings, including homes, offices, restaurants, stores, theaters, and hotels, to name only a few examples.

Building automation systems operate by issuing commands from a control panel (e.g., a keypad) to an output device (e.g., a lamp control). Inexpensive building automation systems are available which use the existing electrical wiring in the building for issuing commands to the output device. The control panel and output device are each plugged into electrical outlets in the home and the control panel issues commands via the electrical wiring in the home. However, the commands may be distorted or lost due to “noise” in the electrical wiring. In addition, such systems are limited to relatively few output devices.

Inexpensive building automation systems are also available in which the control panel issues radio frequency (RF) commands to the output devices. However, RF transmission is typically limited in range (e.g., by government regulation) and is subject to interference (e.g., from other RF devices).

Other building automation systems are available which implement RS232 architecture to issue commands from the control panel to the output devices. The RS232 architecture allows more reliable data exchange between the control panel and the output devices. However, the control panel (e.g., keypad) must be directly connected to each of the output devices (i.e., a point-to-point or so-called “hub-and-spoke” arrangement). Such an arrangement can only be used for short runs and is wiring intensive, making these systems expensive to install and maintain. In addition, the RS232 architecture does not provide for error-handling.

SUMMARY

An exemplary embodiment of Control Area Network (CAN) bus router may be implemented as a system. An expandable building automation system may comprise a control area network (CAN) backbone. At least one CAN router may be connected in-line to the CAN backbone. A plurality of automation devices may be connected to the at least one CAN router for communication over the CAN backbone.

In another exemplary embodiment, CAN bus router may be implemented as a method. An exemplary method of configuring a building automation system, may comprise: providing a control area network (CAN) backbone for a building having a plurality of automation zones, providing at least one CAN router for connecting a plurality of automation devices in each automation zone, and communicatively coupling the plurality of automation devices to one another over the CAN backbone via the at least one CAN router.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a high-level schematic diagram of an exemplary building ion system.

FIG. 2 is an exemplary instruction table for use with in a building automation system.

FIG. 3 is a high-level schematic diagram of another exemplary building automation system.

FIG. 4 is a high-level schematic diagram of exemplary distributed controllers for a building automation system.

FIG. 5 illustrates an exemplary signal which may be issued over a CAN bus in a building automation system.

FIG. 6 is a high-level schematic diagram of yet another exemplary building automation system, illustrating the use of CAN routers.

FIG. 7 is a high-level schematic diagram of an exemplary CAN router for use with a building automation system.

FIG. 8 is an illustration of exemplary CAN routers implemented in an exemplary daisy-chain configuration.

FIG. 9 is a high-level schematic diagram of another exemplary CAN router for use with a building automation system.

DETAILED DESCRIPTION

Briefly, building automation systems may be used to automate various functions in a home or other building (not shown). Exemplary functions may include lighting, heating, air conditioning, audio/visual output, operating window coverings to open/close, and security, to name only a few examples.

An exemplary building automation system 100 may include one or more automation devices, such as, control devices (e.g., a keypad) operatively associated with one or more controlled devices (e.g., a triac board). Control devices issue commands, which in turn instruct the controlled devices to perform a function. By way of example, when a homeowner (or more generally, a user) presses a key on the keypad, the central lighting in the room may illuminate to a predetermined intensity (e.g., 50%) and perimeter lighting in the room may be turned on (e.g., at 100% intensity) to illuminate artwork hanging on the walls.

It should be understood that the foregoing example is provided in order to better understand an exemplary environment in which building automation systems may be implemented. Of course building automation systems may also be implemented with any of a wide range of other types and configurations of automation devices, and for various functions beyond lighting a room, which are now known or that may be developed in the future. The particular types and configurations of automation devices may depend in part on design considerations, which can be readily defined and implemented by one having ordinary skill in the art after becoming familiar with the teachings herein.

In an exemplary embodiment, the automation devices are operatively associated with a control area network (CAN) bus. The CAN bus may comprise a two-wire differential serial data bus. The CAN bus is capable of high-speed data transmission (about 1 Megabits per second (Mbits/s)) over a distance of about 40 meters (m), and may be extended, e.g., to about 10,000 meters at transmission speeds of about 5 kilobits per second (kbits/s). It is also a robust bus and can be operated in noisy electrical environments while maintaining integrity of the data.

It is noted that the CAN bus implemented for building automation is not limited to any particular configuration or number of devices, and may comprise as many as 16,000 or more devices linked over extended runs throughout the building. The CAN bus may also include error handling and bus arbitration, enhancing performance of the building automation system. The speed with which a number of (i.e., one or more) devices may send and receive signals over a single CAN bus is particularly advantageous for building automation (e.g., lights can be turned on and off immediately without recognizable delay).

In addition, more than one CAN bus may be combined to extend the functionality of the building automation system. For example, a general purpose CAN bus may be provided for lighting and another CAN bus may be dedicated to the security system. The building automation system may also be modified for different devices and/or functions, even after the initial installation, allowing the building automation system to be tailored to the user's preferences.

FIG. 1 is a high-level schematic diagram of an exemplary building automation system 100. Exemplary building automation system 100 may comprise a CAN bus 130 for a number of automation devices. For example, one or more control devices 110-113 (also generally referred to herein as control device 110 or control devices 110) may be operatively associated with the CAN bus 130. In addition, one or more controlled devices 120-124 (also generally referred to herein as controlled device 120 or controlled devices 120) may be operatively associated with the CAN bus 130.

It is noted that suitable interfaces (not shown) may be provided for coupling the control device 110 and controlled device 120 to the CAN bus 130 for issuing and receiving CAN signals over the CAN bus 130. Such interfaces are readily understood by those having ordinary skill in the art, and may be readily provided for use with the building automation systems described herein after having become familiar with the teachings herein.

An exemplary CAN bus 130 may be implemented as a two-wire differential serial data bus. The CAN specification is currently available as version 1.0 and 2.0 and is published by the International Standards Organization (ISO) as standards 11898 (high-speed) and 11519 (low-speed). The CAN specification defines communication services and protocols for the CAN bus, in particular, the physical layer and the data link layer for communication over the CAN bus. Bus arbitration and error management is also described it is noted, however, that CAN bus 130 is not limited to any particular version. It is intended that other specifications for the CAN bus, now known or later developed, may also be implemented for the building automation systems described herein.

Before continuing, it is noted that the term “control device” as used herein is defined to include any suitable device (e.g., a keypad, sensor, etc.) which is generally configured to receive input and generate a signal based on the received input. By way of example, control device 110 may be a keypad or keyboard. When the user passes a key (or sequence of keys) on the keypad, one or more signals may be generated that are representative of the key(s) that were pressed. The signal(s), in turn, correspond to a predetermined function (e.g., dim central lighting to 50%, activate security system), as will be described in more detail below.

Control device 110 may be any suitable device and is not limited to a keypad or keyboard. Examples of other types of control devices include, but are not limited to, graphical user interfaces (GUI), personal computers (PC), remote control devices, security sensors, temperature sensors, light sensors, and timers.

It is also noted that the term “controlled device” as used herein is defined to include any suitable device which is generally configured to perform one or more functions in response to a signal issued by a control device. In an exemplary embodiment, the controlled device 120 receives the instruction over the CAN bus 130, as will be described in more detail below. In other embodiments, controlled device 120 may also receive input from sources other than the CAN bus 130.

By way of example, a controlled device may be implemented as a controllable alternating current (AC) switch and associated processing hardware and/or software, collectively referred to as a “triac board.” When the triac board receives an instruction to dim the main lighting from a control device (e.g., a keypad), the triac board causes the main lighting to dim (e.g., to 50% intensity).

It is further noted that the terminology “control device” and “controlled device” is not limited to automation devices dedicated to “control” or “controlled” functionality, although such dedicated devices may also be implemented. In exemplary embodiments, automation devices may also be implemented as “multi-function” automation devices to perform the functions of both a control device and a controlled device. Although a multi-function automation device is not shown separately in FIG. 1, multi-function automation devices are represented in FIG. 1 as control device 110 and controlled device 120. That is, when the multi-function automation device performs the functions of a control device, it is represented in FIG. 1 as control device 110. When the multi-function automation device performs the functions of a controlled device, it is represented in FIG. 1 as controlled device 120.

Continuing now with the description of exemplary building automation system 100, control device 110 and controlled device 120 may be operatively associated with the CAN bus 130 in any suitable manner, including by permanent, removable, or remote (e.g., wireless) link. By way of example, control device 110 and/or controlled device 120 may be permanently linked to the CAN bus 130 by a hard-wire connection. Alternatively, control device 110 and/or controlled device 120 may be removably linked to the CAN bus 130 by a suitable “plug-type” connection (also referred to as a “bus tap”). Control device 110 and/or controlled device 120 may also be remotely (or wirelessly) linked to the CAN bus 130, for example via an RF link.

Building automation system 100 may also comprise a central controller 140 operatively associated with the CAN bus 130. Central controller 140 may also be linked to the CAN bus 130 in any suitable manner, such as described above for control device 110 and controlled device 120.

Central controller 140 may be any suitable device generally configured to receive a signal from control device 110 over the CAN bus 130, and in turn, to issue a signal with a corresponding instruction over the CAN bus 130 for controlled device 120. In an exemplary embodiment, central controller 140 may be reprogrammable, i.e., capable of executing computer-readable program code (including but not limited to scripts), which can be changed to reprogram the central controller 140. By way of example, central controller 140 may comprise one or more personal computers or server computers, microprocessors, programmable logic devices (PLA) such as a field programmable gate array (FPGA) or application-specific integrated circuit (ASIC), to name only a few.

Before continuing, it should be noted that the term “central” in “central controller 140” is used to describe the interoperability with more than one of the control devices 110 and controlled devices 120. It is not intended to limit the physical location of the central controller with respect to the CAN bus 130 (or subnets 131) or the devices on the CAN bus 130.

It should also be noted that central controller 140 may be provided with various ancillary devices, for example, power supplies, electronic controls, input/output (I/O) devices, computer readable storage media, etc. Such ancillary devices are well-understood and therefore are not shown or described herein as further description is not needed for a full understanding of, or to practice the teachings herein.

In an exemplary embodiment, the central controller 140 also performs error checking and bus arbitration functions. Error checking and bus arbitration is defined by the CAN specification, currently in versions 1.0 and 2.0. These functions may be provided to enhance performance of the building automation system 100 by reducing the occurrence of corrupt or lost signals on the CAN bus 130.

As mentioned briefly above, central controller 140 is configured to receive signals over the CAN bus from control device 110, and issue signals with corresponding instructions over the CAN bus for controlled device 120. Central controller 140 may access the instruction from an instruction table 150, as described in more detail below with reference to FIG. 2.

Optionally, building automation system 100 may comprise one or more external link(s) 160. In an exemplary embodiment, external link 160 may comprise a link from central controller 140 to another network such as the Internet via an Internet service provider (ISP). In an exemplary embodiment, external link 160 may be used to import/export the instruction table 200 (e.g., at installation or for changes).

External link 160 may also be used to troubleshoot the building automation system 100. For example, when an error occurs on the CAN bus 130, the central controller 140 may generate an error message which may be transmitted to the building owner and/or a monitoring service (e.g., via email, pager alert, etc.).

Of course, it is understood that the external link 160 is not limited to an ISP link. In other embodiments, the external link 160 may be provided via a local area network (LAN), a wide area network (WAN), an Intranet, or a telephony link, to name only a few examples. In addition, external link 160 may connect to any suitable external device, such as to a laptop computer, personal digital assistant (PDA), pager, facsimile machine, or mobile phone, to name only a few. In addition, external link 160 may comprise a temporary connection for use by a service technician. For example, the external link 160 may comprise a link suitable for connecting a laptop computer to the building automation system 100.

Building automation system 100 may also comprise one or more optional repeater(s) 170, e.g., provided in-line on the CAN bus 130. Repeater 170 may be used to extend the physical length of the CAN bus 130, and/or increase the number of devices that can be provided on the CAN bus 130. For example, repeater 170 may amplify signals and/or “clean” (e.g., improve the signal to noise ratio) the signals issued over CAN bus 130.

Building automation system 100 may also comprise one or more additional busses 131. In an exemplary embodiment, the optional bus 131 is also a CAN bus. In an exemplary embodiment, building automation system 100 may comprise dedicated busses 130, 131. Dedicated busses 130, 131 may be categorized by type of device, area of the building (e.g., first floor, bedrooms), or any other suitable category. For example, a dedicated CAN bus 130 may be provided for all of the lighting devices and another dedicated CAN bus 131 may be provided for all of the security devices. Accordingly, a failure in one CAN bus 130 does not affect operation of the other CAN bus 131.

FIG. 2 is an illustration of an exemplary instruction table 200 for use in a building automation system. Instruction table 200 may be defined based on various parameters, such as the needs and desires of the building occupant. The instruction table 200 may be operatively associated with a central controller for use with a building automation system (e.g., the central controller 140 and building automation system 4100 in FIG. 1). For example, the instruction table 200 may be stored on suitable computer readable storage media accessible by the central controller.

Exemplary instruction table 200 may comprise signal data 205 and instructions 210. Signal data 205 corresponds to the input which may be received by a central controller (e.g., the central controller 140 in FIG. 1). In an exemplary embodiment, signal data 205 comprises the identity of the control device (Device ID) and the type of input received at the control device (Input ID). The instructions 210 identify functions that a controlled device (e.g., controlled device 120 in FIG. 1) may perform when the controlled device receives the corresponding signal data 205.

By way of example, signal data 205 may comprise Device ID=Device 1 and Input ID=Key 1. The instructions corresponding to this signal data 205 may be “Main Lighting 50%” and “Perimeter Lighting ON”. In this example, if Device 1 issues a signal indicating that Key 1 is actuated, the central controller adjusts the “Main Lighting” to 50% intensity, and turns on the perimeter lighting by issuing instructions to the appropriate controlled device(s).

It is noted that the instruction table 200 may be defined in any suitable manner. For example, instruction table 200 may be defined as a code-driven table. However, instruction table 200 is not limited to any particular format and the embodiment shown in FIG. 2 is provided only for purposes of illustration.

In an exemplary embodiment, instruction table 200 may be generic (i.e., applicable to one or more predefined configurations of the building automation system 100). However, in another exemplary embodiment, the instruction table 200 may be custom or tailored to each building automation system 100. A custom instruction table may be defined after the configuration of a particular building automation system 100 is known.

According to either embodiment, instruction table 200 may be modified, reconfigured, or replaced, based at least in part on the changing needs and/or desires of the building occupants. For example, when the building changes occupancy, the instruction table 200 may be changed to reflect needs and/or desires of the new occupants. Modifying, reconfiguring, or replacing the instruction table 200 is particularly advantageous when one or more automation devices are added or removed from the building automation system. Modifying or replacing the instruction table 200 may also be used to change one or more parameters for the automation devices, such as, e.g., defining a new key on a keypad, changing the lighting intensity for a triac board, etc.

With reference now to FIGS. 1 and 2, exemplary building automation system 100 may be operated as follows. Control device 110 and/or controlled device 120 may be configured during manufacture, during installation, or when reconfiguring the building automation system 100. Instruction table 200 is provided for use by the controller 140. Instruction table 200 may also be defined for the building automation system 100.

After the building automation system 100 is configured and ready for use, control device 110 may be operated to receive input (e.g., from the user or other source), and generate signals based on the received input. By way of example, when the user enters input to control device 110 (e.g., by pressing one or more keys on a keypad), control device 110 may issue signal(s) that are representative of the input (e.g., the keys that were pressed). As an illustration, when the user presses the key labeled “Illuminate Artwork”, control device 110 issues signal(s) corresponding to one or more functions to illuminate the artwork in the room. These signals are issued over the CAN bus 130 for one or more controlled devices 120.

In an exemplary embodiment, the signal(s) are broadcast by the control device 110 over the CAN bus 130. That is, signals are received by each of the devices (110, 120, 140) on the CAN bus 130. Each device (110, 120, 140) determines whether it should respond to the signal. It is noted that more than one device may respond to the signal. If the device determines that it should not respond, the device does nothing (i.e., the device “ignores” the signal).

Although addressing may be used, in other embodiments the device may respond even without an address if the signal identifies the device function(s). For example, a light controller may respond to a signal related to lighting and “ignore” signals related to environmental controls (e.g., heating/humidity/air conditioning).

In an exemplary embodiment, only the central controller 140 responds to signal(s) from control device 110. Although each of the devices on the CAN bus 130 receive the signal from control device 110, none of the other devices respond.

The central controller 140 receives the signal from control device 110. Central controller 140 responds by accessing the instruction table 200 and issuing an instruction based on the signal. For example, when the signal data includes Device ID of “Device 1” and Input ID of “Key 2”, the corresponding instructions according to the instruction table 200 in FIG. 2 are “Main Lighting 50%” and “Perimeter Lighting ON”. The central controller 140 issues these instructions over the CAN bus 130.

In an exemplary embodiment, the central controller 140 broadcasts a signal comprising the instructions over the CAN bus 130. The broadcast signal is received by each of the devices (110, 120, 140) on the CAN bus 130, and each device (110, 120, 140) determines whether it can respond to the instructions. If the device (110, 120, 140) determines that it cannot respond, it ignores the instructions.

In the above example, one of the devices (e.g., controlled device 122 in FIG. 1) may be a triac board for the main lighting circuit, and another of the automation devices (e.g., controlled device 123 in FIG. 1) may be a single-pull single-throw switching board (e.g., a switch with associated processing hardware and software) for the recessed perimeter lighting. Accordingly, controlled device 122 responds to the instruction “Main Lighting 50%” by dimming the main lighting circuit to 50%, and controlled device 123 responds to the instruction “Perimeter Lighting ON” by turning on the recessed perimeter lighting. The central lighting in the room dims and the recessed perimeter lighting turns on, illuminating artwork hanging on the walls in the room.

Of course it is understood that the above examples are merely illustrative of exemplary central control systems and methods, and is not intended to be limiting. Indeed, the building automation system 100 is also well-suited for performing more elaborate functions, now know or that may be later developed, as will be readily appreciated by one skilled in the art after having become familiar with the teachings herein.

Exemplary Distributed Control Systems and Methods

FIG. 3 is a high-level schematic diagram of another exemplary building automation system 300. Exemplary building automation system 300 may include at least one control device 310 and at least one controlled device 320 linked over CAN bus 330. It is noted that 300-series reference numbers are used to refer to the like elements shown in FIG. 1 and described above.

Exemplary building automation system 300 may comprise distributed controller(s) (such as distributed controller 400 shown in FIG. 4) operatively associated with one or more of the automation devices. For example, distributed controller(s) may be provided for each control device 310, for each controlled device 320, or for both control devices 310 and controlled devices 320.

Building automation system 300 may also comprise one or more maps 390 operatively associated with a bridge 380 (discussed in more detail below). In an exemplary embodiment, map 390 is stored in computer-readable storage accessible by the bridge 380. The map 390 may also be operatively associated with one or more of the distributed controllers.

Map 390 may be defined in any suitable manner. For example, map 390 may be defined as a text file using a word processor. Indeed, map 390 may be defined as part of an instruction table. It is understood, however, that map 390 is not limited to any particular format.

In an exemplary embodiment, map 390 comprises the identity of each device 310, 320 on the CAN bus 330. Of course, a truncated version of the map 390 may also be used and include only some of the devices. For example, the truncated version of map 390 stored at a controlled device 320 may only identify control devices 310 from which the controlled device 320 will receive signals. As another example, truncated versions of the map 390 may be provided at bridges 380 where the building automation system 300 has more than one bridge 380. Each bridge 380 is provided with a truncated map 390 identifying only devices on the CAN bus 330 that are linked to a particular bridge 380.

The map 390 may be updated manually (e.g., by exporting, modifying, and importing the map 390). Alternatively, map 390 may be updated by automatically detecting or determining which of the devices 310, 320 are on the CAN bus 330. When a device 310, 320 is added to or removed from the CAN bus 330, bridge 380 and/or distributed controllers 400 automatically determine the status of the devices 310/210 on the CAN bus (i.e., whether a device has been added or removed). Bridge 380 and/or distributed controllers 400 may update the maps 390 to reflect any changes.

By way of example, when a device 310, 320 is added to the CAN bus 330, a distributed controller operatively associated with the added device may issue a signal with its device address. When the bridge 380 and/or others of the distributed controllers receive the signal and do not recognize the device address (e.g., it is not listed in map 390), map 390 may be updated with the identity of the added device. Similarly, when a device 310, 320 does not respond, map 390 may be updated to indicate that the non-responsive device has been removed from the CAN bus 330, or is otherwise offline.

If dynamic addressing is used, as discussed above, the bridge and/or distributed controllers may also be used to assign a dynamic address to an added device. For example, bridge 380 and/or distributed controller may assign a dynamic address that is not already being used, and update the map 390 accordingly. The bridge 380 may also issue a signal comprising the dynamic address to the distributed controller of the added device (e.g., as a dynamic address). Similarly, the dynamic address may be removed from map 390 when a device is removed from the CAN bus 330.

Building automation system 300 may also optionally comprise an external link 360. External link 360 may interface with the CAN bus 330 through one or more of the control devices 310, controlled devices 320, and/or bridge 380. Alternatively, external link 360 may interface via a port provided on the CAN bus 330. As discussed above with reference to FIG. 1, external link 360 may be used to import/export instruction table(s), maps 390, etc. External link 360 may also be used to troubleshoot the building automation system 300.

Building automation system 300 may also comprise an optional repeater 370. Repeater 370 may be provided on the CAN bus 330 to extend the physical length of the CAN bus 330. As discussed above with reference to FIG. 1, repeater 370 may be used to extend the physical length of the CAN bus, and/or increase the number of devices that can be provided on the CAN bus. For example, the repeater may amplify and/or clean signals (i.e., by improving the signal to noise ratio) issued over the CAN bus.

Building automation system 300 may also comprise one or more additional busses 331, which may be linked to one another via bridge 380 as shown in FIG. 3. Although not required, the optional bus 331 may also be a CAN bus. As discussed above, building automation system 300 may comprise separate and/or dedicated busses 330, 331 for different areas of the building and/or for different functions.

FIG. 4 is a high-level schematic diagram of exemplary distributed controllers for a building automation system. Distributed controller 400 may be any suitable device configured to process signals (such as the signal 500 shown in FIG. 5). In an exemplary embodiment, distributed controller 400 may be reprogrammable, i.e., capable of executing computer-readable program code (including but not limited to scripts), which can be changed to reprogram the distributed controller 400. One or more of the distributed controllers 400 may also perform error checking and bus arbitration functions for the CAN bus.

Exemplary distributed controllers 400 may comprise one or more microprocessors, PLAs (e.g., FPGA, ASIC), etc. It is noted that distributed controllers 400 may be operatively associated with automation devices, such as, control device 310 and/or controlled device 320, in any suitable manner. In an exemplary embodiment, distributed controllers 400 are provided at, and are directly linked to the automation device (e.g., as part of the same computer board).

In an exemplary embodiment, only the device operatively associated with a failed or otherwise offline distributed controller 400 is affected by such failure (or by being offline). Other automation devices of the building automation system 300 may continue in operation even though one or more of the distributed controllers 400 is no longer operational.

In operation, distributed controller 400 may generate signals. For example, distributed controller 400 may generate a signal comprising an instruction. That is, when control device 310 receives input, distributed controller 400 may use instruction table 410 to generate a signal comprising corresponding instruction(s) for controlled device. Likewise, distributed controller 400 may perform any number of functions for the controlled device. In an exemplary embodiment, distributed controller 400 generates instructions for controlled device based on signals that are received over the CAN bus.

In an exemplary embodiment, the automation devices may each comprise a device address 430. Each device address 430 may be unique to the device. For example, device addresses 430 may be assigned to the automation devices as unique part numbers, although it is noted that the part number need not be numerical. The device address 430 may be provided with each automation device in a suitable memory, although other embodiments are also contemplated as being within the scope of the teachings herein. In any event, no other automation device has the same device address 430, thereby reducing the likelihood that the automation device is misidentified. For example, a triac board is not misidentified on the CAN bus as a security board (e.g., activating an alarm when the user intends to turn on the lights).

It is understood that other embodiments are also contemplated. In another exemplary embodiment, the device address 430 may be unique to a category of devices. For example, each triac board may have the same device address 430, which is different from the device address 430 used to identify electric motor controls. Yet other embodiments are also contemplated and will become apparent to those skilled in the art after having become familiar with the teachings herein.

FIG. 5 illustrates an exemplary signal which may be issued over a CAN bus in a building automation system. Exemplary signal 500 may include an address of the device(s), for example, in an address field 510. Accordingly, the signals 500 may be addressed to specific automation devices, supporting so called “peer-to-peer” communication over the CAN bus even though the signal 500 is broadcast to each of the devices on the CAN bus. Addressing also enables particular automation device(s) on the CAN bus to be reset without having to reset all of the devices on the CAN bus (i.e., only the device(s) identified in the address field 510 perform a reset instruction in field 520).

Although the device address 430 itself may be provided in the address field 510 of the signal 500 to identify automation devices, unique device addresses may be too long to effectively implement, e.g., including ten, twenty, or even more digits. That is, a large address field 510 may reduce the size that can be allotted to other fields (e.g., to instruction field 520). In addition, a signal 500 having a large address field 510 may require significant bandwidth for transmission over the CAN bus 330. High bandwidth signals 500 slow transmission speeds, and may need to be transmitted as multiple packets, increasing congestion on the CAN bus 330.

In an exemplary embodiment, dynamic addressing may be implemented (e.g., dynamic address 420 in FIG. 4) for each automation device or category of devices. That is, each automation (or category of devices) may be assigned a dynamic address 420 that is unique to a particular building automation system. The dynamic address 420 may be shorter than the device address 430 and still uniquely identifies the automation device (or category of devices) in a particular building automation system (or on a particular “leg” of the building automation system).

By way of example, consider three keypads Keypad A, Keypad B, and Keypad C. Keypad A and Keypad B are used in one building automation system (System A), and Keypad C is used in a separate building automation system (System B). Each keypad has a unique device address (e.g., device address 430 in FIG. 4) that is different than any other device. For example, Keypad A may have device address “123ABC,” Keypad B may have device address “123XYZ,” and Keypad C may have device address “456ABC”. According to this embodiment, each keypad is assigned a dynamic address (e.g., dynamic address 420 in FIG. 4) when it is provided in the building automation system. For example, Keypad A is assigned dynamic address “10,” Keypad B is assigned dynamic address “20,” and Keypad C is assigned dynamic address “10.” Although Keypad A and Keypad C both have the same dynamic address (i.e., “10), these keypads are used in different building automation systems (System A and System B) and therefore are still uniquely identified in their respective systems. However, Keypad A and Keypad B are both used in System A, and therefore are assigned dynamic addresses that are unique to System A to avoid being misidentified.

With reference now to FIGS. 3-5, exemplary building automation system 300 may be operated as follows. The distributed controller 400 processes the address field 510 of the signal 500 to determine whether it is addressed to the device 310, 320. By way of example, the signal 500 may be broadcast over the CAN bus 330 to each of the devices 310, 320, as discussed above.

The distributed controllers 400 read the address in the address field 510 and determine whether it corresponds to the device address 430. If the address in the address field 510 does not correspond to the device address 430, the device 310, 320 does not respond. In an exemplary embodiment, the controller 400 stops processing the signal 500, thereby conserving processing power and increasing the efficiency of the building automation system 300. If the address in the address field 510 corresponds to the device address 430, the controller 400 continues processing the signal 500. Again, it is noted that more than one device may respond to a signal.

Signals may also be addressed to all of the devices on the CAN bus 330 (e.g., by setting the address field to null). For example, a signal 500 may be addressed to all of the devices so that the user can readily reset all of the devices on the CAN bus 330 after a power outage. Likewise, a signal 500 may be addressed to groups of devices by including a group identification in the address field 510 or another field (e.g., Field n 540). For example, a signal 500 may be addressed to all of the devices, or particular types of devices (e.g., the lights) or categories of devices (e.g., outdoor lights) so that the user can readily shut all of those devices (e.g., by pressing a single key).

Also in exemplary embodiments, an acknowledgement may be issued over the CAN bus 330 when a signal 500 is received by the device. For example, the device may send an acknowledgement defined by the CAN protocol. Accordingly, if a signal is not acknowledged, the sending device may resend the signal.

In alternative exemplary embodiment, the distributed controller 400 of a receiving device may issue a targeted acknowledgement, by returning a signal 500 with an acknowledgement field 530 to the sending device. The acknowledgement field may comprise an acknowledgement or “ACK” message when a received signal is processed. Such an embodiment may be particularly desirable when more than one signal is delivered over the CAN bus 330 and must be assembled at the receiving device before it can be processed. Likewise, the acknowledgement field may be a negative acknowledged or “NAK” message when the received signal(s) cannot be read or are otherwise unusable. Optionally, an error message may also be generated for the user or service technician (e.g., by a suitable error-processing device on the CAN bus 330 and transmitted via external link 360).

Exemplary CAN Routers

FIG. 6 is a high-level schematic diagram of yet another exemplary building automation system 600, illustrating the use of CAN routers. As discussed above with reference to FIGS. 1 and 3, building automation system 600 may comprise one or more automation devices 610a-g, such as control devices (e.g., keypads) and/or controlled devices (e.g., motors). The automation devices may also include one or more remote transmitters 610f for remotely (or wirelessly) communicating with one or more remote receivers 615. The automation devices 610a-g (also referred to as automation device 610 and automation devices 610) are operatively associated with one another over a network or a plurality of networks, e.g., via CAN routers 670-672 (discussed in more detail below).

The building automation system 600 may include at least one CAN bus backbone. Implementing a CAN bus backbone provides localized wiring, easing installation and troubleshooting. In an exemplary embodiment, the CAN bus backbone is configured as subnets 620 and 625. One or more bridges 630a-b and 635a-b (e.g., a primary bridge and a secondary or “shadow” bridge) may link the subnets 620 and 625 to one another via a local area network 640 (e.g., an Ethernet LAN).

CAN bus subnets and redundant bridges are described in more detail in co-owned U.S. patent application Ser. No. 10/807,930 entitled “Bridge Apparatus and Methods of Operation” of Ogawa, et al., hereby incorporated herein for all that is disclosed. Briefly, the subnet configuration may provide fault protection for the building automation system 600 by rerouting signals around a disconnection in the subnet (e.g., as illustrated at 650). In addition, each bridge in a subnet may be provided with a copy of the operating information for the respective subnet, so that operation of the subnet may be automatically switched in the event one of the bridges fails. For example, operation of the subnet 620 may be switched from the primary bridge 630a to the secondary bridge 630b if the primary bridge fails.

The automation devices 610 may be communicatively coupled to the CAN bus 660, 665 (e.g., in the subnet 620 or 625, respectively) by one or more CAN router(s) 670-672. CAN routers provide a single connection point on the CAN bus for a plurality of automation devices, providing a localized wiring system, making it easier to install the automation devices. If one or more automation device fails, the other automation devices continue to operate. The failure of automation devices do not affect operation of other devices or the CAN backbone, and may be readily replaced without having to turn off power or otherwise shut down the building automation system.

Building automation systems employing CAN routers are also flexible, and may be readily expanded even after initial installation. In addition, troubleshooting is easier and can be done with less sophisticated diagnostic tools.

In an exemplary embodiment, one or more of the CAN routers 670-672 may be implemented as a hub. The term “hub” as used herein to mean a network connection device which communicatively couples devices on the CAN bus, e.g., in a “star” configuration. It is noted that the hub may be a passive hub (e.g., for connecting without adding to the data bits passing through), or an active hub (e.g., for regenerating the data bits to maintain signal strength). The hub may also be implemented as an “intelligent” hub, which includes a processor and basic operating system for handling server or network control operations. In an exemplary embodiment, the hub may also interconnect different types of networks, thereby performing a bridging function. When functioning as a hub, the router sends all of the packets received on each of the ports, out through all of the other ports, without interpretation.

In another exemplary embodiment, one or more of the CAN routers 670-672 may be implemented as a switch. The term “switch” is used herein to mean a network connection device which cross-connects CAN bus segments, while providing each sender-receiver pair the full bandwidth of the network. That is, each port on the switch may provide full bandwidth to a single station, or connect to another switch or hub with several stations. The switch may also be implemented as an intelligent switch, e.g., having a processor and basic operating system for handling server or network control operations.

When functioning as a switch, the router keeps track of all addresses of the connected devices and only sends the packets to a device which are needed by that device. In addition, any packets destined for another device plugged into the same board (and not required by any other device in the system) may be sent only to the addressed device.

In another exemplary embodiment, one or more of the CAN routers 670-672 may be implemented as a strict router. When acting as a strict router, the router checks the address fields of each packet and determines which subnet it belongs to. The router only retransmits it to ports configured to handle the appropriate subnet traffic.

In another exemplary embodiment, one or more of the CAN routers 670-672 may be implemented as a gateway. When acting as a gateway, the router checks each packet to see if it is required to be sent on any of the other non-CAN ports (such as Ethernet or RS232). The packet may be encapsulated for the other interface. The router also monitors traffic from the other router(s) and sends packets out the CAN ports.

It is noted that in exemplary embodiments, the router may be configured to set one or more of the ports to any combination of the above functions (e.g., hub, switch, gateway, etc.).

In addition, one or more of the CAN routers 670-672 may be programmed to automatically reconfigure the baud rate. This means that when a new CAN device is plugged into the router, the router determines what the data rate the new CAN device is operating at, and match the data rate of the router to the CAN device. The router may also be set to automatically alter the data rate to achieve the maximum reliable data rate possible.

Although CAN routers are described above with reference to building automation system 600, it is noted that CAN routers are not limited to use with any particular type or configuration of building automation system. For example, CAN routers may also be implemented in the building automation system 100 described above with reference to FIG. 1, the building automation system 300 described above with reference to FIG. 3, and with any other building automation system implementing a CAN bus.

FIG. 7 is a high-level schematic diagram of an exemplary CAN router 700 for use with a building automation system (e.g., building automation system 100, 300, or 600, discussed above). Exemplary CAN router 700 may be connected in-line to the CAN bus backbone. A plurality of automation devices may be connected to the CAN router 700 for communications with other automation devices connected directly to the CAN router 700 and/or with other automation devices on the CAN bus backbone (e.g., connected to other CAN routers) or in other CAN subnets or other networks (e.g., devices on LAN 640 in FIG. 6).

Exemplary router 700 may include a housing 710, with a plurality of input/output (I/O) ports, such as, e.g., power-in 720, power-out 721, CAN-in 722, CAN-out 723. Any of a wide variety of other types of I/O ports may also be provided (e.g., illustrated as in FIG. 7 “Port n” 725). For example, other types of I/O ports may include a connection for remote (or wireless) control (e.g., an IR or RF receiver), troubleshooting port(s), and status signaling port(s), to name only a few examples.

Exemplary router 700 may also include a plurality of processors 730-734, each linked to the CAN bus backbone (e.g., between the CAN-in port 722 and CAN-out port 723). In an exemplary embodiment, processors 730-734 may be implemented using an SJA2020 processor commercially available from Philips Electronics. The SJA2020 processor has 6 built-in CAN controllers. Other processors that do not include built-in CAN controllers may also be implemented by communicating with any number of external controllers (thereby reducing the number of microcontrollers on the board). Still other types of processors may also be implemented, and are not limited to the SJA 2020 processor.

The processors 730-734 serve several different functions. For example, one processor may be selected to act as the main controller, i.e., for communicating with the bridge (if present). These communications may include notifying the bridge of any alarm conditions on the router (e.g., low voltage). The main controller is also responsible for receiving new firmware from the bridge, and then sending it to each of the slave processors. The main controller also monitors the status of the other processors.

Processors 730-734 may also provide an interface with the CAN backbone and one or more automation devices connected to the processors at device ports 740a-e, 741a-e, etc. The processors may monitor each of the CAN ports, and when it detects that a cable has been plugged in, the processor begins accepting packets and determining how to handle the packets.

In an exemplary embodiment, processors 730-734 may be linked to a plurality of device ports 740a-e, 741a-e, etc. Although any suitable device ports 740a-e, 741a-e, etc. may be implemented, in an exemplary embodiment, the device ports may include standard connections, such as, e.g., RJ-45 ports to ease installation, device replacement, and reconfiguration. In addition, any number of device ports may be provided for each processor, limited only by the number of devices a processor can effectively manage (e.g., typically based on the CAN bus definition).

Electrical power may be readily connected to the CAN router 700, e.g., at port 720, and provided to the processors 730-734. For example, an electrical power source may include local electrical wiring. Optionally, electrical power may be provided via a separate wire in the same cable used to route the CAN bus. Electrical power may also be continued to other devices (e.g., other CAN routers) via port 721.

Electrical power may also be provided to each of the automation devices from the CAN router 700, e.g., via device ports 740. Alternatively, electrical power may be provided directly to the automation device (e.g., using electrical wiring local to the automation devices).

FIG. 8 is an illustration of exemplary CAN routers 800-802 implemented in an exemplary daisy-chain configuration. Exemplary CAN routers 800-802 are shown including processors (referenced generally as 810) and device ports (referenced generally as 820), as described above for the exemplary CAN router 700 shown in FIG. 7. The CAN routers 800-802 may be connected to one another to expand device capacity without having to extend the CAN backbone.

The term “daisy-chain” as it is used herein to refer to the configuration of CAN routers 800-802 means connecting a primary CAN router to the CAN backbone, and then connecting other CAN routers to the device ports. By way of example, primary CAN router 800 is shown in FIG. 8 connected in-line to the CAN backbone, e.g., at 830 and 835. Primary CAN router 800 is also connected in-line to electrical power, e.g., at 840 and 845. CAN router 801 is connected to CAN router 800 at one of the device ports 821, and CAN router 802 is connected in turn to CAN router 801 at one of the device ports 822.

The CAN routers 801 and 802 are shown in FIG. 8 as expansion routers. Expansion routers may be compact, e.g., including fewer processors and device ports. In addition, a daisy-chain port may be provided to connect with the CAN router on the CAN backbone, instead of providing CAN-in and CAN-out ports for in-line configuration on the CAN backbone. However, it is noted that expansion routers 801 and 802 do not need to be implemented for a daisy-chain configuration. In other embodiments, a plurality of CAN routers (e.g., CAN routers 700 in FIG. 7) may be implemented in a daisy-chain configuration, e.g., by connecting the CAN-in port of one CAN router to a device port of another CAN router.

It is noted that more than one daisy-chain configuration may be implemented in the building automation system. For example, CAN router 800 may include a plurality of daisy-chains by connecting additional CAN routers (e.g., CAN router 805) to different device ports (e.g., device port 823) in the CAN router 800.

It is also noted that electrical power may be provided to the CAN routers 801-802 via device port 821. Alternatively, electrically power may be provided to the CAN routers 801-802 from other power sources, e.g., via electrical wiring local to the CAN routers 801-802.

Furthermore, it is noted that daisy-chained CAN routers do not need to be connected to device ports, and may instead be connected to dedicated ports (not shown) in the CAN router 800 provided for making daisy-chain connections.

The daisy-chain configuration may be implemented to extend functionality of the CAN backbone beyond the definition of the CAN bus protocol. That is, the CAN bus protocol may only allow X number of devices (e.g., currently 256 devices, depending on the hardware) on the CAN bus. However, by implementing the CAN routers in a daisy-chain configuration, the processors are linked serially to one another and not directly to the CAN bus. Accordingly, there is no limit to the number of automation devices that may be implemented on the CAN system without the need for repeaters. In other embodiments, repeaters may also be implemented on the CAN backbone, along with the daisy-chain configuration, to further extend functionality of the CAN backbone.

FIG. 9 is a high-level schematic diagram of another exemplary CAN router 900 for use with a building automation system. It is noted that the I/O ports have already been described with reference to FIG. 7, and therefore are not repeated here.

In this embodiment, CAN router 900 includes cascading processors. Cascading processors may also be implemented to extend functionality of the CAN backbone beyond the definition of the CAN bus protocol, e.g., without having to implement a repeater on the CAN backbone. In addition, cascading processors may be implemented in a daisy-chain configuration (e.g., as discussed above with reference to FIG. 8) to further extend functionality of the CAN backbone.

The term “cascading processors” is used herein to mean at least a first processor in the CAN router is connected to the CAN backbone, and one or more additional processors are connected serially to the first processor. In FIG. 9, for example, CAN router 900 includes a CAN processor 910 connected to the CAN backbone, e.g., at connection 915. CAN router 900 also includes cascading processors 920-923, serially linked to the CAN processor 910. The processors (CAN processor 910 and/or cascading processors 920-923) also include a number of device ports (generally referred to as device ports 930) for connecting automation devices.

In addition to the specific embodiments explicitly set forth herein, other aspects and embodiments will be apparent to those skilled in the art from consideration of the specification disclosed herein. It is intended that the specification and illustrated embodiments be considered as examples only.

Claims

1. An expandable building automation system comprising: a control area network (CAN) backbone; at least one CAN router connected in-line to the CAN backbone; and a plurality of automation devices connected to the at least one CAN router for communication over the CAN backbone.

2. The building automation system of claim 1 wherein the at least one CAN router is a hub.

3. The building automation system of claim 1 wherein the at least one CAN router is a switch.

4. The building automation system of claim 1 wherein the at least one CAN router receives a CAN signal over the CAN backbone and automatically multicasts the CAN signal to at least one automation device connected to the CAN router.

5. The building automation system of claim 1 further comprising a plurality of CAN routers connected to one another in a daisy-chain configuration.

6. The building automation system of claim 5 wherein the daisy-chain configuration includes a first CAN router coupled directly to the CAN backbone, and at least one expansion CAN router coupled to the first CAN router.

7. The building automation system of claim 1 wherein at least one of the automation devices includes a remote transmitter connected to the CAN router.

8. The building automation system of claim 7 wherein at least one of the automation devices includes control device issuing signals to a controlled device via the remote transmitter.

9. The building automation system of claim 1 wherein the CAN backbone remains operable even if the at least one automation device is inoperable.

10. The building automation system of claim 1 further comprising at least one CAN processor in the CAN router directly coupled to the CAN backbone.

11. The building automation system of claim 10 further comprising at least one cascading processor in the CAN router, the cascading processor connected serially to the CAN processor.

12. The building automation system of claim 1 wherein the at least one CAN router provides electrical power to automation devices connected to the CAN router.

13. A method of configuring a building automation system, comprising: providing a control area network (CAN) backbone for a building having a plurality of automation zones; providing at least one CAN router for connecting a plurality of automation devices in each automation zone; and communicatively coupling the plurality of automation devices to one another over the CAN backbone via the at least one CAN router.

14. The method of claim 13 further comprising connecting at least one CAN router to a primary CAN router in a daisy-chain configuration.

15. The method of claim 13 further comprising connecting at least one expansion CAN router to a primary CAN router in a daisy-chain configuration.

16. The method of claim 13 further comprising connecting a plurality of CAN routers to a primary CAN router.

17. The method of claim 13 further comprising communicatively coupling a wireless automation device with the CAN backbone via the at least one CAN router.

18. The method of claim 13 further comprising expanding capacity of the CAN backbone without a repeater, while maintaining full functionality of the CAN backbone.

19. A building automation system, comprising: localized communication means for communicating control area network (CAN) signals for building automation; and router means for connecting a plurality of automation devices to the localized communication means.

20. The building automation system of claim 19 wherein the router means is expandable in a daisy-chain configuration.

21. The building automation system of claim 19 further comprising means for maintaining integrity of the localized communication means even if the router means is inoperable.