s7-300 alarm
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One substation of an S7-300 control system in our factory is giving alarms for no reason. The SF light is always on, while the BF light flashes. We can’t see the list of program faults. Temporary issues are resolved by replacing the module. The substation is equipped with 2 DI modules, 1 DO module, and 1 AI module; when I couldn’t figure out what to do at first, I tried changing modules one by one, and by replacing a DI module I resolved the temporary issue. But later on, this problem occurred frequently; the cycle was different – sometimes the tube lasted longer and sometimes shorter. In some months there is 1 month, and in 10 days there is 1 day. I replaced about a dozen modules, and later using the old modules also worked fine. I can’t figure out what the problem is now. I would like to ask the experts here: what might be the problem in this situation, and how can it be resolved? I hope it can address the root cause; otherwise, it will be exhausting. There’s a lot of pressure on production
Your description is too vague. When the CPU gives an alarm, do the downstream IO modules also give alarms? Does the substation communicate via IM? Finally, there is a program that can be connected; in the hardware configuration, one can check the specific alarm information in the CPU diagnostic buffer.
It’s not a CPU alarm; it’s an ET200 IM153-1 alarm
ET200M? Then are you using a redundant CPU of 400?
Online diagnosis can be performed in STEP7 software; generally, it is due to poor contact at the interface.