Siemens S7 Hardware Question

arocon

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Join Date
Oct 2006
Location
Dubai
Posts
171
We are using Siemens S7 CPU 319 F-3PN/DP with ET-200S DP slave module and 4F-DO, 1-FRO module, digital and analog module. We are getting following message in CPU diagnostics:

6:54:41.833 F-I/O depassivated
6:54:37.482 Module ok
6:54:37.333 F-I/O passivated
6:54:37.314 Module problem or maintenance necessary
6:54:37.300 Distributed I/Os station return
6:54:37.280 Module ok
6:54:37.615 Distributed I/O Station Failures

These alarms are getting repetitively. From the alarm list ‘Distributed I/O Station Failures’ alarm appears first. But I do not see in the panel from the LED any I/O station failures. But I see an input is sometimes going 0 which is supposed to be 1 in the digital input module. From this input it has crated a memory and from this memory it has connected with safety program. Could this input make problem? To find out I modified in the program so that it does not affect the safety program when the input goes to 0. But still I am getting the above alarm repetitively in the CPU diagnostics.


Could anyone help me what could be problem?

Also can I jumper one input direct at Input module (voltage is 24V).
 
Looks like the ET200s is losing communication with the main PLC. Is it on profibus?

A poor connection can cause the failure and recovery of the comms to happen so fast that you cannot notice the BF led.

The default retry for comms failure is 2, so only if there are 3 successive failures between the CPU and the ET200s you will notice the distributed I/O failure. The system will keep running until the communication is completely interrupted.
 
I had a similar problem and spend many hours to find out what is wrong. I had safety plc and becouse I wasn't sure my offline project I just uploaded hardware, did small change and downloaded hardware again. From this moment problems had started. I got those messages as you have. I reloaded HW many times, I also reloaded safety project, uploaded compiled, recompiled, everything. Nothing was able to fix the problem. Then I took my first uploaded HW, download and still nothing.
Siemens support had no idea why is happening like that. They check project and could not find anything wrong.
Finally I took my original (not the one I uploaded) offline Project, download HW with safety and problem disapear. NEVER UPLOAD HW AND DOWNLOAD AGAIN IF YOU HAVE SAFETY PLC!!!

Question: do you have actual project? If yes then compare online/offline your System Data and see in details what differences you have. Let me know what you have. Did you also downloaded safety or HW?
 
Last edited:
Rafal, yes i have actual project. Nothing uploaded from PLC. Safety program in PLC, otherwise safety system would not work.
 
How old is the installation? Are there many nodes on profibus or just one?

How long is the profibus cable going from the PLC to the ET200s?

You must connect a profibus analyser on the CPU and see what exactly is happening. Incase you dont have one you have to resort to hit-and-try method.


The first thing i will ask you to check is proper termination on the connectors, termination resistors switched ON.

try posting a sketch of the network layout of your system.
 
What is the speed that profibus is currently communicating at?

I have had issues with the default 12mbps that our systems come in with and have taken them down to 1.5mbps. But I'm not sure how this would affect your system.
 

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