Dear Friend

I got error like this. My system includes a S7-400 and ET200 CPU. In that ET200 there are some analog input modules (6ES7331-7PF11-0AB0), the system works normally. At that time, the production line was down for maintenance and an incident occurred that day. The first module has a flashing SF light. Then about 4 hours later, 2 more modules also encountered the SF flashing error. When checking the signal, interference was detected for a period of 2 hours and then the signal was lost. When checking the channels of the module, the voltage in the channels of the module is close to zero. I want to know the possible cause of signal noise and module failure. Thank you. I sent more pictures. everyone please help

Hello,

in my general opinion after little bit looking and searching something strange at screenshots, no any over temperatures are there, if I see limits. It could be important to know exactly at what time was that brake to maintanance to do something. date and time because although some strange oscilations are there I don't see any over signals with set limits. Do more research also as process is expected, maybe some Valve or solenoids movement with expected place of that temperatures can be interesting to see. I don't know and pls understand that you ask for something what is simply not possible, only personal with process knowledge and that place need to be invovlved to this. ZIP screenshots. You need save that screenshots to be more lower with size so you can ZIP them to not be higher than is allowed here. To my basic opinion, there must be some very high temperature or high Voltage somewhere depended to that sensors with place. also interesting is what that maintanance team did exactly heh. I don't know if they also maybe brake some wires some where but it is then clear to signal with value 0 or specific as sensor declares with 0 signal. Your attention simply must point to that sensors where are placed or be maybe some where connected also in some cabinets, who knows. What is interesting is that also RTD signals are included in this problem looks like. What about PLC diag buffer for sure to see? Do you have spare modules same to quickly replace and see? Correctly shielded cables ?

One good tip now As Maintanance do some log in book of maintanance or procedures defined by company internal rules (date/time/procedure), it can be then clear what they did, what they tested and other things with this. Hope you all do serious maintanance procedures as are required. This can be helpful to you to find also some problem.

Hello,

no other way as only you can find the cause of problem. At my shoes, it is required to check and discover power supply lines (I already sugested that previously generally) and correct wiring, grounding of supplys. Due your simple (not still good) description it looks like that power supply cables take some long distance from supply to exact place of usage, correct? You can see and understand that we can here talk about hundreds of posts and this comes to nothing. If your maintanance did nothing during brake, give them task to check seriously all lines, finally. It looks to me that some junctions or cable brakes/connections again are somewhere existed, especially you can pay attention to that ones that are depended to your faulty modules. really I don't know what other I can recommend to you. Investigation take also place with to think due sensor specification (RTD/TC) what other signal in vicinity/place can iritate that sensors signal in that time and with what reason. welding... I hope your cables are that correct/reliable/correct and not cheap only without any shielding and proper connections. Pay attention to this and think that we don't have crystal ball