Siemens CPU

kashif_mahmod87 · Aug 29, 2013

Dear,

in my company, we are using siemens plc Cpu 314-2dp.
One day we remove the two machines out of 10 from a single line. when we removed the line, the bus fault and signal fault appear. But the cpu is running and our line is also running.
Can we run the line forever with this cpu status or future something can be happend?

Our plc program is ok. CPU is ok and it is running but the signal fault and bus fault LED's flashing.
is it effect our program? or effect to cpu execution? can anyone help.

DrJS · Aug 29, 2013

It's not right, but it will run

The Signal and Bus fault, lights on the PLC are configuration errors, because the config is looking for nodes and I/O that are now removed. You should be ok as long you have OB82,OB87,and OB122 in your program, which you must already have, or the plc would have stopped.

kashif_mahmod87 · Aug 30, 2013

thanks alot for reply.
the program having OB's which you mentioned. My question is, this bus fault and signal fault will effect the program or not? and we can run the plc program as long as possible.

davenardella · Aug 30, 2013

The suggestion, obviously, is to fix the hardware configuration : in the future you may not see further serious problems.

Anyway yes, your program can run.

The Bus processor is indipendent from the CPU, it refreshes the I/O bus, if something is wrong an error is reported to the CPU which calls the errors OBs if present; if they are missing it goes in stop mode.

kashif_mahmod87 · Aug 30, 2013

thank you so much.

wimpiesplc · Aug 30, 2013

One day we remove the two machines out of 10 from a single line. when we removed the line, the bus fault and signal fault appear. But the cpu is running and our line is also running.

Obviously you guys had no clue about what you were doing and are lucky it kept running...
and "SF" means system failure, not signal fault

balash · Aug 31, 2013

wimpiesplc said:
Obviously you guys had no clue about what you were doing and are lucky it kept running...
and "SF" means system failure, not signal fault

well, if we're gonna push it, it's System Fault not System Failure

jvdcande · Aug 31, 2013

balash said:
well, if we're gonna push it, it's System Fault not System Failure

Well, since it's obvious they didn't have a clue about what they were doing, the difference between System Failure and System Fault, as big as it might be (or become), didn't bother them anyway

Luckily for the OP ("original poster") the system didn't fail, it only had a fault, which was dealt with in the program. Hooray for the OP (meaning "original programmer" here)!

Kind regards,

balash · Aug 31, 2013

OP (meaning original programmer) saved the day.

true. :site:

PeterW · Aug 31, 2013

You can use SFC12 to activate and de-activate nodes.

If you are temporarily removing nodes and don't want the red lights flashing, then maybe create blocks that call SFC12 for each node and a button to enable/disable the nodes.

When you remove a node, you could de-activate the node via the button, red light goes away, and when you put it back in re-activate it to re-enable faults.

It could also be done with a soft switch in the PLC, which maybe wiser.

hagos · Sep 3, 2013

SF Fault

Greetings sparkies,

In his case if a NODE is removed, and the CPU is running though the BF & SF LED's are lighting, the programmer must have programed OB86 as well.

Cheers

Siemens CPU

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