BF in Siemens CPU 315-2DP

azby

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Join Date
Oct 2022
Location
Offshore
Posts
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Hi
We were having a few power cuts and the CPU would not work. I had to reset the memory and he CPU would read from the memory card and start working.During the last power cut we lost he program and reset the memory but we are getting a blinking BF and SF. Not sure whether the memory card itself is corrupted
Ye to check connecting a PC and the configuration
Any ideas pls
 
Many possibilities exist.

1. Has the program been downloaded since it was "lost"?
2. What do you see in the CPU's Diagnostic Buffer?
3. Do any network devices have a BF light or are powered off? This would explain the BF light.
4. Check Profibus address DIP switches on network devices. Are any set incorrectly?
 
Exact type no of the CPU ?
How did you 'reset the memory' ?
If you have STEP7, you should go online and check both hardware diagnostics and the diagnostics buffer.
 
Hi
The PLC is Siemens CPU 315 - 2 DP
It is connected to two small PCs which are on the arms of the chair by DP
One of them failed and was replaced. Now we have the BF light on after one of the PC was replaced
 
Hi
The PLC is Siemens CPU 315 - 2 DP
It is connected to two small PCs which are on the arms of the chair by DP
One of them failed and was replaced. Now we have the BF light on after one of the PC was replaced

pic1.jpg pic2.jpg pic3.jpg
 

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Check Profibus addresses of the two computers.
Check your Profibus cables and terminating resistors.

Please give as much information as possible about the computers.
How they are connected to Profibus?
 
OB82 and OB86 are called because of missing DP station 5.
OB86 is called for both failure and return of DP station 5, so it is an intermittent error.

So the PC must have been setup as a DP slave.
It can be cable, connector, or termination error.
Or it can be some other fault with the PC.

Not a lot of info to work with here...
 
You have a problem with profibus and, most likely, it is a cabling fault. Profibus networks require a terminator at each end which can be measured accross the two wires as 220 ohms per terminator.

To check with a resistance meter:
1) disconnect all profibus plugs
2) measure end to end continuity of both the A, B wires and also the screen
3) measuring from one end: turn off all the terminators = measure open circuit between A and B and A,B to screen
4) turn on the terminator at the far end = measure 220 ohms
5) turn on the terminator at the near end = measure 110 ohms

Good luck
 
Manglemender - Thanks for the info. Will take the cables and check continuity and the terminators. Is it possible you can suggest a wiring diagram with terminators. One master / 2 slaves with master in middle

JesperMP - Thanks. Both PC's were slaves and it was DP station 6 which was changed while DP station 5 was untouched.

RVaughan - Both PC are Nexcom - Model NISE2010 with ApplicomIO PCIboard 32K

Node address 5 (RHS) and 6(LHS). Node5 T ON ---- PLC T OFF ----- Node6 T ON

I am going to remove the Profibus cables out of the panel and check them with meter as I have doubts on the Terminating switches

Thanks will keep you updated
 
If the PC is a DP slave, there must be some hardware and software on the PC to achieve this functionality.
Both hardware and software must run, if they dont it will also count as a the DP slave not being available.

Again ... you dont provide much information to work with.
All that we know that it a PC that is a DP slave.
 
Both PC are Nexcom - Model NISE2010 with ApplicomIO PCIboard 32K

Attached some photos - not very clear

Pls let me know what further info is required

Thanks

pic1.jpg pic2.jpg pic3.jpg pic4.jpg pic5.jpg
 
So now we can see that the PCs are setup with OPC Servers. Then there must be an OPC Client that connects to the OPC Server and accesses the OPC tags configured for the DP slave interface.
If not, that will also be counted as that the DP slave is unavailable.

This is not a simple system, who originally set it up ?
You should have them come and troubleshoot the error, or at least contact them.
 
Thanks for all your advice and support
Manglemender - Thanks for the info. Physically checked cable with meter, looks OK
JesperMP - As you said it looks like something else messed up in the last power cut
Will be checking with the OEM support team
Learnt a bit during this discussion
Thanks again
 
Hi
Finally sorted the problem
One of the slave PC which was replaced had problems with the Profibus card
Replaced the card from the old one and everything was back to normal
Error msg: The board number 1 was initialized with a different version of applicomIO. Please initialize to update it
Will open a different thread for it
Thanks to all
 

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