1769-L18 Fault Issue

Bullzi

Lifetime Supporting Member
Join Date
Jun 2012
Location
Colorado
Posts
1,530
Hi everyone,
Last week when I was starting up a panel with a L18 someone shut off the main breaker to my panel. After the processor powered back up it was faulted out. The fault message said that it couldn't communicate with my Point I/O Modules. So I re-seated the modules and TB's, re-powered the unit and used Studio 5000 to reset the fault. Off it went and everything has been good.



Until now!! I think the same thing may have happened and of course I am not there this time. I had the Electrician power down and re-seat all the cards and TB's. He powered back up and everything appears good but the unit has not started to run. Any chance that the program could have been wiped out? All the lights appear to be in the proper status but the unit is not running and the HMI is not showing good data so I am guessing it is not communicating.


Any ideas on why this Fault happens? What should I be looking for or what should I replace? I have 2 other units like this in the same area with no issues so it is related to this one panel as far as I can tell.


Thanks for the advice!!
 
You can configure the IO modules to fault the controller or not if it occurs during run time. If the controller faulted again, depending on what it is, it may not clear. Typically I only allow the controller to fault on IO card comm loss. All field io is setup not to fault the controller, but has alarms on the hmi if not communicating
 
Here is what I think is happening...

Power on to machine....

The controller faults because the link to the point io is established After the plc boots.

Power is maintained, link is established to point io, you reset the fault, life is good

Power is cycled to machine, controller faults because the link is not established right away

This is going to happen every time power is cycled unless.

In the module properties you should see a check box with regards to controller faults if the module faults. I’m. It going to tell you to uncheck the box because due diligence needs to be done to ensure that this solution is safe to resolve the issue.
 
Is the L18 the one where the point IO can attach to the processor?

If so I see now how this is perplexing. I assumed that you were using the point IO with an Ethernet adapter.
 
Last edited:
Is the L18 the one where the point IO can attach to the processor?
Yes it is!! I wonder if I got a bad processor or a bad Point I/O Terminal Block and it losses connection from time to time.

I don't know what happened this time. Last time it was a power fail that hosed it up. This time maybe power but maybe not. The site is running off a generator and it didn't go down. So it could be a related to a bad transformer or ???
I am hoping that maybe someone had this happen before and can say what they did to fix it.
 
I will pull all the point IO apart and check all the bus connections and see if you can see any damage. If nothing is obvious I would then start swapping the rack pieces out one by one to a known good system and see what happens. Hopefully you used the removable terminal blocks!!
 

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