Abstract: A communication system has a number of nodes connected to a serial data bus. Nodes communicate with each other by transmitting dominant and recessive bits during bit intervals as taught by the CAN (controller area network) arbitration protocol. According to the CAN arbitration protocol, any dominant bit transmitted during a bit interval causes the bit value received to be a dominant bit regardless of the number of recessive bits being sent. The system is arranged so that two or more nodes each respond to a report query message sent by one of the nodes, with a report message sent simultaneously by each of the nodes. The headers (leading bits) of each of the report messages sent by nodes responding to a report query message are the same, allowing arbitration on a trailing node data field. This results in the message having the numerically largest (or smallest) node data field value to survive arbitration.

Abstract: An autodiscovery system for configuration information about an HVAC system being provided to a controller or thermostat. Configurations or parameters may be autodiscovered from communicating equipment. Also, this equipment may be manually selected and set without affecting the autodiscovery status of the remaining equipment. There may also be non-communicating equipment that does not provide information to the thermostat. However, the thermostat may control the non-communicating equipment via an equipment interface module.

Abstract: Flow is managed within a fluid delivery system. One illustrative fluid delivery system is a zoned HVAC system. In one illustrative embodiment, a method is provided for controlling the airflow and thus the heat or cool delivery rate to a room serviced by the zoned HVAC system. The zoned HVAC system includes a duct system that is in fluid communication with various rooms through zone dampers. An open/closed state of the zone dampers is determined, and an open time for at least selected zone dampers are adjusted based on the state of the dampers.

Abstract: A system has a plurality of nodes communicating with each other on a serial data path using dominant and recessive signal levels. A dominant signal level sent on the data path by any of the nodes creates a dominant signal level on the data path irrespective of the number of recessive signal levels sent by other nodes. The dominant and recessive signal levels form a series of bits organized into messages by the nodes. Each sending node senses the signal level on the data path bit by bit, and if different from that sent by that sending node, halts further sending of signal levels by that sending node. A priority value generator in each node provides a priority signal encoding a value whose magnitude indicates a relative priority. A message priority module in each node receives the priority signal, and stores the priority value in predetermined leading bits of the message to be sent.

Abstract: A communication system has a number of nodes connected to a serial data bus. Nodes communicate with each other by transmitting dominant and recessive bits during bit intervals as taught by the CAN (controller area network) arbitration protocol. According to the CAN arbitration protocol, any dominant bit transmitted during a bit interval causes the bit value received to be a dominant bit regardless of the number of recessive bits being sent. The system is arranged so that two or more nodes each respond to a report query message sent by one of the nodes, with a report message sent simultaneously by each of the nodes. The headers (leading bits) of each of the report messages sent by nodes responding to a report query message are the same, allowing arbitration on a trailing node data field. This results in the message having the numerically largest (or smallest) node data field value to survive arbitration.

Abstract: A system has a plurality of nodes communicating with each other on a serial data path using dominant and recessive signal levels. A dominant signal level sent on the data path by any of the nodes creates a dominant signal level on the data path irrespective of the number of recessive signal levels sent by other nodes. The dominant and recessive signal levels form a series of bits organized into messages by the nodes. Each sending node senses the signal level on the data path bit by bit, and if different from that sent by that sending node, halts further sending of signal levels by that sending node. A priority value generator in each node provides a priority signal encoding a value whose magnitude indicates a relative priority. A message priority module in each node receives the priority signal, and stores the priority value in predetermined leading bits of the message to be sent.

Abstract: A controller area network (CAN) has a plurality of nodes connected to transmit and receive data over a serial data line using an interface circuit to connect the node to the data line. Each interface circuit includes an isolation element, typically a diode, to connect the interface circuit to the data line. An indicator element in the interface circuit is powered when the node is transmitting. The isolation element in each node prevents other nodes while transmitting, from powering the indicator element in its node.

Abstract: A controller area network (CAN) has a plurality of nodes connected to transmit and receive data over a serial data line. An AC power source is also connected to each node. Each node senses the AC power waveform and synchronizes bit transmission and bit detection with the waveform. In a preferred embodiment, each node includes a circuit that detects zero crossings by the AC waveform, providing two accurately synchronized bit intervals per complete AC cycle. A preferred version of the invention includes hardware and software that detects miswires of the node to the data and power lines.

Abstract: A method of communicating between a plurality of devices in a controller area network is disclosed. The method includes authorizing a first device to transmit messages with a first identifier over the network, the first device transmitting a first message with the first identifier and a first value, and the devices which receive the first message assuming the first value as their respective values. The method may be used with a number of devices and a listening device in a system. At startup of the system, any device which saved its value in a non-volatile memory will become the master of the identifier and transmit a message with the value over the network. Devices which did not save their values in non-volatile memories will transmit requests for the data value. If they do not receive any response, they will become the master and transmit messages with their data. Devices which receive the message will assume the value as theirs.

Abstract: A detector for detecting, in images of camera scanned scenes, edges which extend generally parallel to the scanning lines. Accordingly, by comparing an undelayed signal to a first signal delayed by slightly more than one scan line, a differential can be obtained at a 45 degree angle going downward from the left to the right of the image. By delaying a second signal slightly less than one scan line, the differential becomes 45 degrees going downward from the right to the left of the image. These differentials are utilized to detect edges extending parallel to the scan lines.

Abstract: A self contained apparatus is utilized for direct movement on and across a roof surface to lay on the roof surface a continuous sheet or roofing material being removed from a roll guided at each of its ends by this apparatus, and being heated, before being removed, by a heating assembly pivotally supported by the apparatus and pivotally adjusted, so the distance between the roll and the heating assembly is maintained. An inclined A frame of the apparatus has a handle at its apex, and bottom opening slots at its lower ends to fit over the ends of a shaft on which the roll of roofing material is positioned. There is a depending wheel assembly below the handle serving to complete the triangular support of this self contained apparatus. The inclined A frame is pivoted about the wheel assembly to clear the bottom opening slots from the shaft ends and vice versa, when a roll of roofing material is being supplied, withdrawn, and/or adjusted to a different set of slots.