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 a PLC and a communication module includes a sensor; an addition cycle module: the output status register of the addition cycle module, the The number of status registers is the same as that of the sensor, and the status registers have and only one state that remains on at the same time, and the remaining status registers are in a closed state; data loading module: the registers are used as normally open contacts to start data Loading module, the data loading module is used to load and transmit the reading instruction of the sensor; the sending module; the sending module is provided with a buffer, and the buffer is used to receive the reading instruction of the sensor loaded by the data loading module; receiving Module: the receiving module is used to receive sensor data. The invention realizes the serial communication between a plurality of sensors and the plc, and avoids conflicts between a single communication module and a plurality of sensors in data communication.

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