Patent ID: 7787485

Claim:
A method of transmitting a high-priority digital message via a communication link, the method comprising the steps of: transmitting regular-priority digital messages between a plurality of control devices including a master control device, a first control device, and a second control device; the master control device transmitting a first regular-priority polling message to the first control device; the first and second control devices simultaneously transmitting a respective break character by asserting the communication link for an amount of time during a predetermined time period following the first regular-priority polling message to signal that the first and second control devices have respective high-priority digital messages to transmit; the master control device detecting the transmission of the break characters; suspending the transmission of the regular-priority digital messages between the plurality of control devices; the master control device determining a Poll ID of the first control device in response to detecting the assertion of the communication link; the master control device transmitting a report-request message to the first control device using the Poll ID of the first control device; the first control device transmitting the respective high-priority digital message in response to the report-request message during the suspension of the transmission of the regular-priority digital messages; the master control device subsequently determining a Poll ID of the second control device; the master control device transmitting a report-request message to the second control device using the Poll ID of the second control device; and the second control device transmitting the respective high-priority digital message in response to the report-request message during the suspension of the transmission of the regular-priority digital messages.