Patent ID: 7752280

Claim:
A response time-out detection method based on master-slave protocol architecture, which calculates the time required for a detection device functioning as a Modbus master to receive a response from a slave device in response to a Modbus request sent by the detection device based on Modbus communication protocol, the method comprising the steps of: (a) start detection; (b) said detection device sends a Modbus return query data function and subfunction code to said slave device, and records a request sent time; (c) said slave device receives the Modbus return query data function and subfunction code sent by said detection device; (d) said slave device determines whether or not to support the return query data function, and then proceeds to step (e) if yes, or step (f) if not; (e) said slave device executes the return query data function and sends an accurate result response, and then proceeds to step (g); (f) said slave device sends an exception response and then proceeds to step (g); (g) said detection device receives the accurate/exception response from said slave device and records a response received time; (h) calculate the response time-out based on said request sent time and said response received time; (i) determine whether or not to run a next detection and return to step (b) if yes, or proceed to step (j) if not; (j) calculate the precise response time-out from said response time-outs which are gotten from said slave device in response to a predetermined number of the Modbus requests; and (k) end the detection; wherein said master-slave communications architecture is one of Modbus RTU and Modbus ASCII.