Establish mobile data communication between PLC and Scada software(serial)

Overview

     Scada software is a special software for data acquisition and process control. They are the software platform and development environment at the monitoring level of industrial automatic control system. They use flexible configuration methods to provide users with software tools for quickly constructing industrial automatic control system


     The communication serial port of PLC supports Modbus RTU protocol (Omron can choose hostlink protocol). The communication process of Modbus RTU protocol adopts the way of master-slave question and answer, and its acquisition cycle can be set flexibly, which is suitable for mobile data communication.


     The 4G DTU developed and produced by our company can be used to establish reliable data communication based on 4G network between Scada software and industrial field PLC, so as to realize wireless remote monitoring and data acquisition
 
Application layer protocol: Modbus Protocol

     The communication serial port of PLC supports Modbus RTU protocol (Omron can choose hostlink protocol). The communication process of Modbus RTU protocol adopts the way of master-slave question and answer, and its acquisition cycle can be set flexibly, which is suitable for mobile data communication.
 
 
Establish mobile data communication between PLC and Scada software

    The following takes the widely used Siemens S7-200 with Scada software connected through 4G network as an example to introduce the implementation process.

  1. Set PLC Serial Port to MODBUS slave mode

  2. PLC connects DTU through 485 interface

    3. The serial port of S7-200 is DB9 interface, in which pin 3 is connected to pin A of DTU ,and pin 8 is connected to pin B of DTU.


  3. Set DTU connection comway virtual serial port software

    4. The user's computer can only access the Internet and install comway virtual serial port software to realize mobile data communication through comway platform. The schematic diagram is as follows:



    Comway virtual serial port software can add up to 128 virtual serial ports on each computer, and multiple DTUs can be mapped to the same virtual serial port (as long as the Modbus addresses of the connected devices are different), the Scada software can establish data communication with 500-1000 MODBUS devices through DTUs at the same time


  4. SCADA software creates a new I/O device based on choosed virtual serial port
 
Apply broadly
    Any serial port equipment, such as instrument, transmitter and RTU, can establish mobile communication with Scada software in the above way.