ProfiBus Grrrrrr...

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Apr 2004
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Israel
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My customer has 2 identical machines with Siemens S7-315-2dp controllers. Each controller talks to 2 remote racks over ProfiBus. I want to add a WAGO 750-8206 as a slave to the ProfiBus network.

Before I went to the field I set up an S7-315-2dp to talk with the WAGO. On my desk we were able to get the whole thing going in about 10 minutes.

Out in the field things didn't go so well. My colleague spent a whole day on this and couldn't get it to work. The ProfiBus network LEDs are all green. Disconnecting the WAGO causes a fault. Reconnecting the controller clears the fault. The only thing is that data doesn't transfer.

I took a look at this today and wasted an additional 2 hours getting nothing to work. Everything indicates that communications should be working but they're not.

What am I missing?

Thanks,

Yosi
 
If the DP LEDs are green - its working according to how its is configured.
Have you done a Ctrl-D for the device in Step 7?
Checking the WAGO its seems to be a programmable device - Is the program loaded? Does the program map the IO as you require?
Is the device in the run mode?
 
Like Mike said "...its working..."
So on your desk- how did you transfer I/O data?
When you write to outputs on the Wago where did you see Inputs on the S7?
and vice versa

post some screen shots of your S7 config and Wago config
 
I contacted WAGO and they told me that if the mapped variables are not used in the program then the data will not be transferred. When we set this up in our office we looped back some watchdog data that I set up in the Siemens. This is missing from the customer set-up. I'll put it in tomorrow and see if it gronks.

Thanks!
 
You should check if the process image defined in the cpu properties includes the address area of the remote IO. You can find that in the CPU properties under clock i think. You could also try addressing the remote IO addresses using P in front of the address, i.e. PIW300.

If you configured the Wago remote IO address range outside the CPU process input/output image, then the CPU does not scan these addresses. No data is transferred but you dont get a Profibus-DP fault.
 
I contacted WAGO and they told me that if the mapped variables are not used in the program then the data will not be transferred. When we set this up in our office we looped back some watchdog data that I set up in the Siemens. This is missing from the customer set-up. I'll put it in tomorrow and see if it gronks.

Thanks!


If it is Safety IO, then what the WAGO team said is correct. Safety IO is not scanned in a Siemens PLC unless it is used in the safety program, even if it just something as simple as reintegration logic.
 
The WAGO guy was correct. I wrote Outval := Inval and the communications came to life.

Thanks for all of your help and a wonderful New Year to you all.

Yosi
 

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