Nisar Ahmed

Dear Experts,

Our plant is equipped with several SIEMENS CPU 416-3 but we are facing one very strange problem with one unit. During downloadingafter minor changes in the program, it got stopped.

I am enclosing here diagnostic buffer errors.

Please guide me why this happening and what could be the remedy.

Thanks & Best Regards

Dear Steve,

We are facing this problem from beginning (Commissioning), If we not touch the program,CPU works fine. But some time needs to bypass some signals in the PLC program.After this type of small modification when we download theFC to CPUit got stop mode, trip the plant.

Afterstop mode CPU shows INTF and does not come backto RUN mode untilwe download the complete program again.

Please guide me what is the standard procedure to check the program errors completely.

gre_m

Hello Nisar Ahmed


strange that your processor will start a very long time. Perhaps this is due to late initiation of additional devices. In addition, should enter into your program OB80 and the OB85. Also it is necessary to increase the size of the diagnostic buffer to a maximum of 3200 bytes.

VishP

Dear Ahmed,

It's important to know that what was the modification done, I guess, additional logic functions did not finish execution and due to that scan time exeeded the limit. Check the logic again and find out why the additional logic did not finish.
Can you also send the modification you made in the program?

There are some IO access errors also........so anotherquestion, have you only donwloaded the modified FC/FC/OB or complete program downloaded with HWconfig? If this is so, check the backup in which you modified or else check the input module or remote i/os.

Feedback is alway appreciated.

Regards,
Vishp.