I need help: how can an independent PLC system achieve remote DCS control?
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If that’s achieved, won’t the independent module stop working? Can it be achieved once the channel issue is resolved?
Generally, an additional communication card that supports communication with third parties is added to your standalone PLC system, and DCS communication is used to control the PLC
It was the same before, but only communication was possible; remote control was not feasible.
It depends on whether the PLC was configured to read only from that point or to both read and write from it. If it’s set to read only, then it can only be read; control is not possible
For remote control, an Ethernet communication module can be installed on the PLC; subsequently, an RJ45-to-fiber optic device is added inside the cabinet, and a fiber optic-to-RJ45 device is used on the computer side. The upper-level software can then directly read data from the PLC. Of course, communication can also be utilized, with both sides adhering to the same protocol, addressing schemes being established, and read/write procedures defined, thereby enabling DCS to remotely control the PLC as well
If DCS hardware control is used, it can be connected to the DCS hardware via Modbus or Profibus interfaces. If it can be read directly via the DCS HMI, OPC is recommended. The transmission speed and interference are much lower.
If communication between the PLC and DCS has been established but remote control is not possible, it is basically because, as mentioned on the 4th floor, during configuration the DCS only reads data from the PLC without writing to it. Furthermore, the communication method is not reliable; for important remote control points, hardwired connections are generally used instead of communication.
Based on your transmission distance, determine an appropriate communication protocol and link medium, and then select the communication module for your PLC.