Building management system with digital modules for sensors and controlled devices

Abstract

A system for monitoring and controlling building equipment includes building equipment operable within a local operating environment to affect or measure a variable state or condition of a building, a controller configured to send and receive digital messages for communicating with the building equipment, and a plurality of digital modules configured to be installed in the local operating environment and physically attached to the building equipment. Each digital module includes a digital communications interface configured to communicate with the controller using the digital messages, an analog communications interface configured to communicate with the building equipment using analog signals, and a signal converter configured to convert between the digital messages and the analog signals. The system further includes a communications link physically connecting the controller to the digital communications interface of each of the digital modules and configured to transmit the digital messages between the controller and the digital modules.

What is claimed is: 
     
         1 . A system for monitoring and controlling building equipment, the system comprising:
 a plurality of devices of building equipment configured to be installed in a local operating environment and operable within the local operating environment to affect or measure one or more variable states or conditions of a building;   a controller configured to send and receive digital messages for communicating with the plurality of devices of building equipment;   a plurality of digital modules configured to be installed in the local operating environment and physically attached to the plurality of devices of the building equipment within the local operating environment, each digital module of the plurality of digital modules comprising:   
       a digital communications interface configured to communicate with the controller using the digital messages; 
       an analog communications interface configured to communicate with one or more devices of the plurality of devices of the building equipment using analog signals; and 
       a signal converter configured to convert between the digital messages and the analog signals; and
 a communications link physically connecting the controller to the digital communications interface of each of the plurality of digital modules and configured to transmit the digital messages between the controller and the plurality of digital modules. 
 
     
     
         2 . The system of  claim 1 , wherein the communications link comprises a multi-conductor cable comprising:
 a first conductor configured to transmit the digital messages between the controller and the plurality of digital modules; and   a second conductor configured to supply power from the controller to the plurality of digital modules.   
     
     
         3 . The system of  claim 1 , wherein each digital module comprises a power converter configured to:
 receive power from the communications link at an input voltage;   convert the power into an output voltage different from the input voltage; and   output the power at the supply voltage to the one or more devices of the building equipment with which the digital module communicates via the analog communications interface.   
     
     
         4 . The system of  claim 1 , wherein:
 the plurality of devices of the building equipment comprise a sensor configured to measure a variable state or condition and output an analog signal indicating a value of the variable state or condition; and   the plurality of digital modules comprise an input digital module physically attached to the sensor and configured to generate a digital message comprising the value of the variable state or condition based on the analog signal and transmit the digital message to the controller via the communications link.   
     
     
         5 . The system of  claim 4 , wherein the input digital module is configured to:
 generate a sender address of the digital message identifying the sensor or the input digital module as a sender of the digital message;   generate a recipient address of the digital message identifying the controller as a recipient of the digital message; and   generate a payload of the digital message comprising the value of the variable state or condition measured by the sensor.   
     
     
         6 . The system of  claim 1 , wherein:
 the plurality of devices of the building equipment comprise a controlled device configured to receive an analog signal and operable to affect a variable state or condition based on a value of the analog signal; and   the plurality of digital modules comprise an output digital module physically attached to the controlled device and configured to generate the analog signal based on a digital message received from the controller via the communications link and transmit the analog signal to the controlled device.   
     
     
         7 . The system of  claim 6 , wherein the output digital module is configured to:
 monitor the digital messages transmitted via the communications link for a digital message addressed to the output digital module or the controlled device;   process a payload of the digital message addressed to the output digital module or the controlled device to determine a value of a control signal for the controlled device; and   generate the analog signal for the controlled device based on the value of the control signal indicated by the digital message.   
     
     
         8 . The system of  claim 1 , wherein:
 one or more of the plurality of digital modules is a physical device comprising a processing circuit having a processor and memory;   the analog communications interface and the digital communications interface are physical interfaces of the physical device; and   the analog communications interface is physically coupled to the one or more devices of the plurality of devices of the building equipment with which the physical device communicates using the analog signals.   
     
     
         9 . The system of  claim 1 , wherein:
 one or more of the plurality of digital modules is a virtual device running on hardware of a device of the building equipment with which the virtual device communicates using the analog signals;   the digital communications interface is a physical interface of the device of building equipment; and   the analog communications interface is a virtual communications interface within the device of the building equipment.   
     
     
         10 . The system of  claim 1 , wherein the communications link physically connects the controller to each of the plurality of digital modules in a single chain or loop. 
     
     
         11 . A method for monitoring and controlling building equipment, the method comprising:
 sending a digital message from a controller via a communications link physically connecting the controller to a plurality of digital modules;   receiving the digital message at a digital communications interface of an output digital module of the plurality of digital modules, the output digital module installed in a local operating of a controlled device and physically attached to the controlled device within the local operating environment;   converting the digital message into an analog signal at the output digital module;   transmitting the analog signal from the output digital module to the controlled device within the local operating environment of the controlled device; and   operating the controlled device within the local operating environment to affect a variable state or condition based on a value of the analog signal.   
     
     
         12 . The method of  claim 11 , comprising determining a recipient of the digital message based on a recipient address of the digital message received at the digital communications interface of the output digital module via the communications link, wherein:
 the digital message is converted into the analog signal by the output digital module and the analog signal is transmitted from the output digital module to the controlled device in response to determining that the recipient of the digital message is the output digital module or the controlled device; and   the digital message is ignored by the output digital module in response to determining that the recipient of the digital message is not the output digital module or the controlled device.   
     
     
         13 . The method of  claim 11 , wherein:
 the output digital module is a physical device comprising a processing circuit having a processor and memory;   the analog communications interface and the digital communications interface of the output digital module are physical interfaces of the physical device; and   the analog communications interface of the output digital module is physically coupled to the controlled device.   
     
     
         14 . The method of  claim 11 , wherein:
 the output digital module is a virtual device running on hardware of the controlled device;   the digital communications interface of the output digital module is a physical interface of the controlled device; and   the analog communications interface of the output digital module is a virtual communications interface within the controlled device.   
     
     
         15 . The method of  claim 11 , wherein the communications link comprises a multi-conductor cable, the method comprising:
 sending the digital message from the controller to the plurality of digital modules via a first conductor of the multi-conductor cable; and   supplying power from the controller to the plurality of digital modules via a second conductor of the multi-conductor cable.   
     
     
         16 . A method for monitoring and controlling building equipment, the method comprising:
 receiving an analog signal indicating a value of a variable state or condition measured by a sensor at an analog communications interface of an input digital module physically attached to the sensor, wherein both the sensor and the input digital module are installed within a local operating environment of the sensor;   converting the analog signal into a digital message comprising a value of the variable state or condition measured by the sensor at the input digital module within the local operating environment of the sensor; and   transmitting the digital message via a communications link connecting a digital communications interface of the input digital module with a controller and with a plurality of digital modules configured to communicate via the communications link.   
     
     
         17 . The method of  claim 16 , comprising:
 generating a sender address of the digital message identifying the sensor or the input digital module as a sender of the digital message;   generating a recipient address of the digital message identifying the controller as a recipient of the digital message; and   generating a payload of the digital message comprising the value of the variable state or condition measured by the sensor.   
     
     
         18 . The method of  claim 16 , wherein:
 the input digital module is a physical device comprising a processing circuit having a processor and memory;   the analog communications interface and the digital communications interface of the input digital module are physical interfaces of the physical device; and   the analog communications interface of the input digital module is physically coupled to the sensor.   
     
     
         19 . The method of  claim 16 , wherein:
 the input digital module is a virtual device running on hardware of the sensor;   the digital communications interface of the input digital module is a physical interface of the sensor; and   the analog communications interface of the input digital module is a virtual communications interface within the sensor.   
     
     
         20 . The method of  claim 16 , wherein the communications link comprises a multi-conductor cable, the method comprising:
 transmitting the digital message from the input digital module via a first conductor of the multi-conductor cable; and   supplying power from the controller to the plurality of digital modules via a second conductor of the multi-conductor cable.