Method for rapid communication transmission and data processing between PLC and upper computer

Abstract

The invention provides a method for rapid communication transmission and data processing between a PLC and an upper computer. In an application occasion where the monitored data volume of the PLC is large and the data change is little, in each communication data packet, a plurality of data registers are occupied as state registers and are used for transmitting changed data information of the datapacket to the upper computer; in the PLC, a space is opened, and a temporary storage data packet is placed; the temporary storage register in the temporary storage data packet is compared with the register corresponding to the current data packet, and the status bit of the current data packet with the changed data is negated, so that the data packet with the changed data is read emphatically, andthe reading speed and the processing speed for the changed data by the upper computer are remarkably improved; and time delay caused by the fact that the upper computer issues the data packet and reads the information is avoided, and recording errors of the action sequence of remote signaling displacement in a traditional method are avoided.

Description

technical field [0001] The invention relates to a method for improving PLC transmission and processing efficiency, belonging to the PLC application field. Background technique [0002] PLC has a very wide range of applications where the amount of monitoring data is large and the data changes little, such as the wind and hydropower system of a subway station. Its monitoring of wind and hydropower is based on the BAS (Building Automation System, hereinafter referred to as BAS) Controller, hereinafter referred to as PLC) to monitor. [0003] The data monitored by the PLC is stored and transmitted by registers, and a register usually occupies two bytes. PLC communication is usually based on the MODBUS communication protocol. A packet of data in a normal message has 125 registers, that is, 250 bytes. There are usually three packets of digital input data monitored by PLC in a subway station, and more than ten packets of analog input data. It takes 300 milliseconds to query one p...

AI Technical Summary

Problems solved by technology

If the number of registers contained in the data packet is increased, although the number of data packets can be reduced, the number of communication links established and the link time will be reduced accordingly, but the increase in the length of the message will greatly increase the possibility of communication failure, resulting in the need for repeated communication. , wasting communication time

[0004] In the traditional method, the upper computer still reads each data packet sequentially even if there is no changed data, which is a waste of time. Under unfavorable circumstances, the host computer has just finished reading a data packet, and the data packet changes, and the host computer needs to poll the data packet for a circle before it can read that the changed data is a data packet. If the data packet has more than a dozen , the time delay for the host computer to feed back the changed data is the time to read more than a dozen data packets, resulting in slow refresh of the changed data

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