Control Net Problem

dbucher

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Join Date
Sep 2004
Location
Montana
Posts
11
Has anyone seen this before? I seem to have lost control of one of our 1794.oa8 modules. The data table in the plc seem seems to be working fine. I have no control net errors or faults. I swapped out the the oa8 module with a know good one and it still didn't work. I also swapped out the base, no luck there either. I also changed out the anc15 flex I/O module to no avail. The network sees the module, everytime I pull the module I get a fault. I can see it with controlnet, no errors. The scanlist config looks good. The input and output size is set to 4 and the module is in slot 3. Another clue is that this was working before and some how just stopped.

Any help would be greatly appreciated.
 
Most of flex problems related to the connectors.
I've seen situations when connector problem between base 2 and 3 caused module failure in slot 5.
Disassemble flex rail and reassemble it.

Also it is possible your adapter failed
 
Thanks for the tips so far.

The owner of the the module is a control logic plc 5.

I'll try pulling the bases apart and reconnecting. I haven't tried that yet...
 
dbucher said:
Thanks for the tips so far.

The owner of the the module is a control logic plc 5.

I'll try pulling the bases apart and reconnecting. I haven't tried that yet...
Click to expand...
Check for bent pins while you have them apart...flex is very flaky.
 
Is the network properly scheduled?
Perhaps somehow you lost the Controlnet schedule information?
Did this work at one time? and quit? or is this a new installation?
 
The rest of the conrol net is up and running. This did work at one time. This is the only module not working.
 
It has got to be a base with a bent pin. Did you reschedule the network while this problem was there? If so, you need to get the card working again, then reschedule the network in order to regain control of the card.


David
 
As far as I know the network hasn't been rescheduled. The network does see the card, when I pull the module I get a fault on the ANC-15 module. I know that the pins on this module are good cause I checked them when I change the base troubleshooting. I haven't pulled the whole flex rack apart checking for bent pins though. The flex rack is set up like this ANC-15, three 1794-IA16 modules then my problem the 1794-OA8 then in slot 04 a 1794-IE8 module. When I go online with control net is sees everything with now errors. I hope this helps..
 
Are there multiple processors on the network? Is it possible that the processor that was supposed to own it was power cycled or switched out of run mode and another processor took it over? This happened to me in a classroom setting when we had 6 controllogix processors each with their own I/O, but all connected via ethernet. Another student inadvertently added one of my output cards to his controller. An hour later when I put mine in program mode to dump in a program, his controller had control of the card and I could not get it back!
 
Thanks for all the help so far.

There is only one processor on this particular network.

I still haven't been able to check all the base modules for bent pins yet, line is running.
 
I'm out of ideas, but please let me know what you find... I'm about to deploy a system here with about 35 CNet nodes, with all kinds if I/O (including Flex).
I'd like to learn from your experience :)
 
Checkout Rockwell Knowledgebase Application Note G63041298. I have seen this cause the problem before but only during the initial comissioning of a system.

If that is not the problem then it is possible that there is a defective base somewhere in the rack more than likely at a slot before the affected module. I doubt a bent pin unless someone has taken the rack apart since it was installed. Bent pins problems usually show up when first putting the system on line, however a cold solder joint in one of the bases could cause a problem at any time. I have seen this problem in the past and it was caused by a defective base two slots before the module that lost control.
 
Earlier today I had a flex input module (1794-IA16) that would not communicate to my PLC5/30 after a control system upgrade. I only had bit 3 on in the data table and should have had bits 0-4 all on. We swapped the module first, then the base, and even the ASB before finally finding a BENT PIN on one of the 1794-TB3 base modules two slots over from the one that didn't work. I bet that's what you'll find.
 
Again I want to thank all you for your help.

right now I'm kinda in a holding pattern. We only take this line down every two weeks so that's when I'll get my next chance to do some real troubleshooting. When I fix this problem I will report back on this thread. Again Thanks for all your ideas.....
 

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