SLC 500 Fault

SeanLee

Member
S
Join Date
Mar 2004
Location
Minot, ND
Posts
122
I have a SLC 504 CPU that faulted i changed the cpu and works now but would like to know what happened.

Lights on the CPU did this:

First all the light are on except the FLT and BAT light then those 2 come on and the others turn off. they alternate on and off like this

Thank You
 
The next time it happens go online with the processor (assuming you have the software) and look under processor status - errors. That will tell you what happened.

There is a pretty good chance there is nothing wrong with the processor you changed. A lot of different things can cause a fault and most of them have nothing to do with the processor itself. When you have time I would put it back in and re download the program into it.
 
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That pattern sounds like a hardware failure during the power-up Self Test process.

RA Tech Support should be able to tell you which hardware subsystem that pattern indicates failed, but the practical conclusion is that the controller must be replaced.
 
I did try going online with the processor but RS links could not find. Thought maybe was something wrong with my communications so i went to another machine and linked right up. So i was unable to see the Status bits in the procrssor. I did look up chap 10 of the manual and did not see that combination of lights in there.
 
Disconnect the battery and wait a few minutes. This will delete the program and you should be able to see the processor as default in RSLinx. I have had this happen to me and found I could reuse the processor but the fault would happen again. It could be the powersupply.
 
The hardware failure self-test LED sequences aren't in the user manual because they aren't field-repairable. Not being able to "see" the controller over a communication network would be consistent with a hardware failure.
 
I actually had the same exact problem yesterday on a 5/04 - it was a hardware failure. There was a conduit right above the processor and it was leaking water into the SLC.
 
DBLD99 said:
There was a conduit right above the processor and it was leaking water into the SLC.
Click to expand...
Murphy strikes again.
Sorry, but that made me chuckle.. glad you figured it out quickly.(y)
 
Murphy strikes again.
Click to expand...
Not really. The real Murphy's Law is more of a defensive SAFETY warning against bad designs. I owe a debt to ol' Murphy to correct this common misconception, wherever it occurs.

The Real Murphy's Law:
"If there's more than one way to do a job, and one of those ways will result in disaster, then somebody will do it that way."

For more information on West Point graduate, WWII Pilot, and Aerospace Safety Engineer Edward A Murphy, Jr, go here:

http://en.wikipedia.org/wiki/Edward_A._Murphy,_Jr.
 
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one of the reasons why I always place the conduits at the bottom of any control cabinet. Wish management here would stress the same standard when they install new equipment. Ah well
 
mordred said:
one of the reasons why I always place the conduits at the bottom of any control cabinet. Wish management here would stress the same standard when they install new equipment. Ah well
Click to expand...

There are times when you have to think about that too, like when the whole system is mounted against a load bearing block wall, got to be careful how man holes you may drill through the bottom of that wall.

I only mention this because I have seen a wall collapse.
 

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