Hello everyone,

I need some help.

In the processor CPU417-4H I am getting a BUS2F alarm(LED going red). The IM153-2 node just before the processor is fine (as BUS1F and BUS2F LED are not glowing). There is no abnormality in the optical couplers as well. However, I am unable to go online and the machint is not getting started.

What shall I do?

Its urgent.

Regards

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Split from problem of breakage of communication at random intervals.

Hello sanchit;

Anytime a SF or BUSxF is active on the CPU (even on redundant systems) the CPU's diagnostic buffer starts logging error messages that contain information on what causes the fault.

A BUS2F LED indicates a fault on the Profibus-DP network, possibly linked (in the diagnostic buffer) to a OB86 call. Open the diagnostic buffer and locate the messages related to OB86.

Note: OB86 is a diagnostic OB treating the Failure of an expansion rack, DP master system or station for distributed I/Os.

If you have a problem understanding the cause of the problem, you can save the contents of the diagnostic buffer ("Save As Text") and attach the relevant entries here on the forum, so we may be able to look at them and help you out.

Hope this helps,

Daniel Chartier