Free port communication polling system and method based on PLC and communication module

Abstract

The invention discloses a free port communication polling system and method based on a PLC and a communication module. The free port communication polling system based on the PLC and the communicationmodule comprises sensors, an addition cycle module, a data loading module, a sending module and a receiving module. The addition cycle module outputs state registers, the number of the state registers is the same as that of the sensors, only one of the state registers is kept in an on state at the same time, and the rest of the state registers are in an off state; the registers are used as normally open contacts to start the data loading module, and the data loading module is used for loading and transmitting reading instructions of the sensors; the sending module is provided with a buffer area, and the buffer area is used for receiving the reading instructions of the sensors loaded by the data loading module; and the receiving module is used for receiving sensor data. According to the invention, serial communication between the plurality of sensors and a plc is realized, and conflicts generated when data communication is carried out between a single communication module and the plurality of sensors are avoided.

Description

technical field [0001] The invention relates to the technical field of sensor data transmission, in particular to a free port communication polling method based on a PLC and a communication module. Background technique [0002] At present, the traditional polling method adopts timer polling or counter polling, which is characterized in that the data sending module SEND-PTP is triggered by the cycle output rising edge, and the enabling terminal REQ of the data receiving module is in the normally open state; its cycle The judgment method of switching is the address bit of the sensor receiving the data, that is, after the receiving buffer receives the return data of the first sensor, the communication of the second sensor is carried out, and so on, until the last sensor returns to the first sensor to continue the cycle; [0003] The disadvantage is that if a sensor in the middle reports an error and does not receive correct data, the communication will be interrupted. Therefore...

AI Technical Summary

Problems solved by technology

[0003] The disadvantage is that if a sensor in the middle reports an error and does not receive correct data, the communication will be interrupted. Therefore, it is generally necessary to add a timeout reset program so that the program can jump back to the sensor No. 1 for re-execution in the event of a long-term failure, but it will result in the data of other sensors in this period. also uncollected