First aid, 485 communication issues
Thread Content
First question: The PLC is a Siemens 300; when the 485 connector is connected to the communication card, both the CPU and I/O cards lose power. The same problem occurs even after replacing the communication card. The DCS is from Zhejiang University’s Control Systems Department. When this 485 connector is used with another PLC, everything works normally. Why is this happening?Second question: The data from the refrigeration unit is transmitted to the DCS via 485 communication. There are no alarms on the PLC side, but some alarms appear on the DCS screen, although in reality there are no actual alarms. These apparent alarms are related to digital signals, while there are no alarms related to the data itself.
Third question: The PLC of the air compression unit transmits data to the DCS via 485 communication, but the data received differs significantly from what is displayed on the DCS. Please help resolve this issue. I would appreciate it if you could provide videos for learning about DCS as well as some software. Thank you
For the second and third questions, there might be interference; perhaps the conversion between high and low bits of the data wasn’t done properly?
Did it appear suddenly or has it been like this all along?