Allen Bradley SLC-500 Output Board issues

SLB251180

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Experts,

I have an issue with an Allen Bradley SLC-500 Output Board.

The PLC is going through it ladder logic correctly and the Output terminal six is lit but i am getting no output from the card on Output 6. See attached, i am getting an Output from Output 9 which is also lit on same Output Card

Is there any repair/fuse i can replace, or does the module need replaced.

Thanks in advance.

SLB
 
I can't see the type of card if it is relay then it's probable the relay is damaged or if solid state the output is faulty i.e. transistor/triac. The chances are you will have to replace the card or repair it, alternatively if there are spare outputs of the same type and on the same potential you could reprogram that particular output to another one
 
I can't see the type of card if it is relay then it's probable the relay is damaged or if solid state the output is faulty i.e. transistor/triac. The chances are you will have to replace the card or repair it, alternatively if there are spare outputs of the same type and on the same potential you could reprogram that particular output to another one


+1 for Parky. We had a lot of those at a plant I worked at, along with some Micrologix, and those guys fried outputs all the time. They'd brick the ML, and we were always changing modules on the others when we ran out of spare outputs on them. I asked them why they were trying to run a 2 or 3 amp hydraulic valve solenoid or other high current devices on these cards, or why they didn't put interposing relays in the circuit, and they had no answer for the first question and "the panel is too small" for the second question. I simply walked away--all the way back to Michigan.
 
Thanks for the reply, I did think it will be a replacement required. Making sure I was not missing anything obvious.

Logic ladder is controlled from head quarters so will need to replace the card, not allowed to re programme unfortunately.

SLB
 
Couldn't help noticing that on the first pic it looked like the output LED was not on for that output are you sure that it was, Have you tried to disconnect the wire in case the output is being dragged down, also I have replaced output transistors and relays on a number of PLC Cards, can't remember what types on AB but on one Omron plc we had to replace some relays at the rate of one every month or so and these were available in RS, however we eventually replaced the PLC with a Mitsubishi, however the one ordered was relay output when I ordered transistor (lots of operations a day), however as it was programmed in the schedule we had no time to order the correct one but it lasted 5 years without a single relay giving up.
 
Couldn't help noticing that on the first pic it looked like the output LED was not on for that output are you sure that it was...

Agree none of the outputs are lit, cant see the LED's in the second pic but guessing 9 is lit (true)
 
Thanks for the reply, I did think it will be a replacement required. Making sure I was not missing anything obvious.

Logic ladder is controlled from head quarters so will need to replace the card, not allowed to re programme unfortunately.

SLB


I would think that one would want some interposing relays anyway. They certainly extend the life of any outputs on a controller. I worked out west and they did that. Engineering spec. Even for a mA output like a lamp. Certainly seems like a hardware issue and not a programming change.
 
I would think that one would want some interposing relays anyway. They certainly extend the life of any outputs on a controller. I worked out west and they did that. Engineering spec. Even for a mA output like a lamp. Certainly seems like a hardware issue and not a programming change.


I agree, I've been using the AB 700-HL terminal block relays lately for interposing purposes and they're awesome. They're 6.2mm (1/4") wide so you can have a whole block of them that only takes up a couple of inches in your panel.
 
Experts,

I have an issue with an Allen Bradley SLC-500 Output Board.

The PLC is going through it ladder logic correctly and the Output terminal six is lit but i am getting no output from the card on Output 6. See attached, i am getting an Output from Output 9 which is also lit on same Output Card

Is there any repair/fuse i can replace, or does the module need replaced.

Thanks in advance.

SLB

You have to replace the module, but I believe that DC output card is repairable.

As for using interposing relays, I would recommend it for situations where the duty cycle is not too high or when the load device is not inside the same panel.

For cases where high duty cycle or local low power devices are being driven and interposing relays are not called for, you could opt for fusing the outputs either individually or one fuse for each of the common wires supplying voltage to the card.

Since you have some spare terminals on that card, you could edit the logic and move the wire to one of your spare spots.

First, I would make sure the load driven by that transistor is okay before you fry another spare point, but that's the approach I would lean toward (move to a spare) as long as your company policy and regulations don't forbid making such a change.
 
FWIW, I can see the little red lights on outputs 6 and 9, albeit very faintly. Since you can't change the program and move the output, you will have to swap the card. Make sure that the device attached to that output is not shorted or faulted, or you may destroy another output in the process.

I did notice that the battery light is lit on your processor. You might want to make sure that is taken care of before you power down for the swap, or at least have a very current backup on hand.
 
FWIW, I can see the little red lights on outputs 6 and 9, albeit very faintly. Since you can't change the program and move the output, you will have to swap the card. Make sure that the device attached to that output is not shorted or faulted, or you may destroy another output in the process.

I did notice that the battery light is lit on your processor. You might want to make sure that is taken care of before you power down for the swap, or at least have a very current backup on hand.

Mikey,
What size monitor do you have? I zoomed in on mine (24") and I dont see it... I do agree with the battery

EDIT: looking at it again, I do think I may see something, but if its that faint I think the card is shot or the rack and its getting a low voltage

closeup.png
 
Last edited:
Mikey,
What size monitor do you have? I zoomed in on mine (24") and I dont see it... I do agree with the battery

EDIT: looking at it again, I do think I may see something, but if its that faint I think the card is shot or the rack and its getting a low voltage


I definitely see both 6 and 9 lit up, but they are fainter than on the other cards.
 
I agree, I've been using the AB 700-HL terminal block relays lately for interposing purposes and they're awesome. They're 6.2mm (1/4") wide so you can have a whole block of them that only takes up a couple of inches in your panel.




Finder makes those relays for AB. I am not sure about your area but around here I can get the finder relays much cheaper. The only difference is the color and the expensive name on them. I have even put a Finder relay in an AB base before when it went bad.
 
Finder makes those relays for AB. I am not sure about your area but around here I can get the finder relays much cheaper. The only difference is the color and the expensive name on them. I have even put a Finder relay in an AB base before when it went bad.

This does not shock me at all, as the saying goes, you can find better than AB but not more expensive.
 

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