Dear Friends,

we are using a S7315 PLC with Profibus DP slaves around 12 nos in one of our equipment. today all equipments connected with the system goes on alarm mode and when we checked all the slaves become faulty in Hardware config online checking in simatic manager and after some time it goes back to ok.

for a test when we turned one of the middle slave termination to on position again the all slaves goes to fault (red slash comes in online HW config) & individual module information is showing module not found in all slaves. it should only show the faulty devices after the termination. but it shows all slaves are faulty.

my question is in this type of hardware configuration how we will identify the correct faulty slave device & how we can correct / solve this issue of showing only all slaves fault?

Looking forward to hearing from your valuable feed back / replies

Hi,

normally you have one Startpoint and one Endpoint of you DP-Bus. Here are the terminations on and all other terminations must be set to off.

If you turn on the termination at one of you i.e. Slave 8, all other slave (9,10,11,12) will not be reachable to your PLC but the slaves 1-8 should be online...

It looks like your DP-Signal will not be OK, so all other Slaves have an error.

Towome

BINZ_AUTOMATION

Dear Friends,

we are using a S7315 PLC with Profibus DP slaves around 12 nos in one of our equipment. today all equipments connected with the system goes on alarm mode

 Hello,

 Start from CPU Profibus cable and plug,

 and

 https://support.industry.siemens.com/cs/document/26996747/diagnostic-package-pniodiag-for-diagnostic-evaluation-for-profibus-dp-and-profinet-io-(step-7-v5-x)?lc=en-WW

Hello,

The most important thing is to keep the CPU in ON when there have a Profibus node/s fault. That fact will helps in the way of recognizing the faulty node/s. 

When an error occurs the CPU looks for the corresponding Error OB and starts it. If the OB is not loaded, the CPU goes to STOP. Two ways:

1. Download an empty OB if you only want to prevent the CPU to stop.

2. Programmed reaction (OB) to the error.

Here in forum have a lot of threads...

The other thing is the way of connection in Profibus chain. In case the terminating resistor is ON in node number X all the next segments are disconected...

Read more about SFC12 or SFC51...

Best regards,

Hristo Mihalev

hi,

Check the grounding of the whole system and the shield of the bus. I had a failure like this some years ago. The reason was a PB-node that had an insufficient grounding. In this case there could be a compensating current through the shield of the PB-cable, that disturbs the signal.

Also avoid stubs on PB.

hope this helps,

regards,

hello Ste39, 

the link you have given will be an useful one . i just go through it seems to be a good solution to trace out. thanks will try

Hi mopSO4 ,

seems to be a reason. will check.. thanks

BINZ_AUTOMATION

hello Ste39, 

the link you have given will be an useful one . i just go through it seems to be a good solution to trace out. thanks will try

 Hello BINZ_AUTOMATION,

If you like this block in addition there is another FC from our friend IBN-Service have a look:  

Additional function to filter the FB126 PNIODIAG - Entries ...