Sohail Riaz

fx3u FX3U Stop Reading Channel Data

5 posts in this topic

Hello Everyone, 

Need help with reading channel data of FX2N-4AD with FX3U Cpu. I have added all the logic and it works also. Problem is that, FROM function stop reading/fetching data from FX2N-4AD after some time i.e couple of hours and value just hang. Like 502 or something, untill you reset the whole PLC. What could be the problem.

For the further info,

-I have connected the FX2N-4AD on the right of fX3U-64M.

-There are two extension blocks FX2N-16EX and FX2N-16EYR also added to the right of FX3U-64M

-Order of mounting....FX3U-64M > FX2N-16EX > FX2N-16EYR > FX2N-4AD > FX2N-4AD

 

I have tried using the 2nd special module connected at the end, but It showed similar problem after few hours of running. THis shows that both Special blocks fx2n-4ad are okay. There is something wrong with PLC maybe? Please help

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Edited by Sohail Riaz

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Have you checked that you're not writing over D0-D3 /D110 etc? ??

I would first check if it is in the PLC or the module.
Have you monitored the BFM 9-12 when this problem occurs? (Online- monitor - buffer memory batch.)

Hmm as the second module is producing the same problem I guess it is not in the module.
 

 

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Sorry for the responding late.

 

No I am not writing over D0 to D3 or D110. 

I monitored the D0 to D3 in logic through Monitor function. Didn't use the Buffer memory batch monitor function though. In logic monitoring It just hang after few hours. All other input and output function correctly.

For further troubleshooting i am thinking to add a mechanical relay or indication with a simple timer onto any output of Extended output module. (I am not using any input or output on the extended modules connected to PLC for now. These are spare). This way i will monitor that when the analog input from block hang, then what is the behavior of Extended output module. What you suggest further?

 

Is it possible that the two modules added in between CPU and 4AD i.e 16EX and 16EYR could be faulty causing the communication error?

Edited by Sohail Riaz

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Strange issue. If the module couldn't be reached the PLC should give an spec mod error.
I would monitor the BFM just to make sure the problem is at the module side.

I can't think of anything which could produce this behavior accept for disabling the channels. 
Are you sure it couldn't be the source of the analog signals which is stopping ?


 

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When the hang issue occurred, i removed the Transducer wire 4-20mA, and checked its ouput through multimeter, it was giving output fine around 8.5mA. I connected the wire again to module but still it didn't show the value. However To be sure i may connect the Transducer output 4-20mA to any Display indicator and then connect to PLC in series. This way it will make sure that issue is module or not.

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