furnaceRP

OD212 Card Outputs not powered

7 posts in this topic

Posted (edited)

Hello!

I'm running into a problem with a malfunctioning OD212 output card on my PLC. 

I figure the problem has something to do with my wiring, because I've put 2 different cards in with the same results. The card is unable to switch any of the relays I have as outputs although the indicator lights on it are functioning as expected. The setup it is in is: A PA202 power supply, followed by a CJ1M CPU13 CPU, 2 ID211 input cards, and 3 OD212 output cards. The bad card is the second OD212. All of the other cards work fine, it's just this one that's been having problems. 

8 of the terminals on the bad card are hooked up to relays that each draw 0.02A and two more are attached to relays that draw 0.05A. So in total that's 0.26A if all the outputs are on at the same time (which they never will be.)

I saw someone was having a similar problem to me on the forum, which was solved by switching out the PA202 supply, but that didn't work in my case.

I don't think the problem lies with the PLC or the card's placement in the rack because I switched the card's position with the one next to it (output card 2 switched with output card 3) and tested that card (output card 3 in output card 2's place) without hooking it up to the original wiring and it worked just fine. However, I was still getting the same issue with the bad card even though it was in a different position, leading me to believe that I fried it somehow.

Some other quirks of the bad card are that its outputs do not turn on and off with the indicator lights like how the other OD212s do. Below is a link to a video that shows this. The bad card has already been switched with the one next to it in the video - so it's on the end, but it's original position was second to last.

https://youtu.be/wTvvGCHFpsc ( you may want to watch it at half speed )

So what I'm wondering is: how am I frying these cards / Is the problem easy to fix or will I have to send them to Omron?

Thanks in advance!

 

Edited by furnaceRP

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This a PNP Output Module.  It will need both sides of the 24VDC.  Watch the precaution about reverse polarity.  The load may still operate.

 

OD212.jpg

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I already have 0v connected to A8 and 24V connected to B8. This is correct, right? It's the same wiring I have for all the other OD212 cards and they work fine.

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So I took the thing apart and I've been doing some poking around. It seems like the card has two sides, the 24V power side and a 5v?? control side, which interface with each other through a couple of ps2811-4 photocouplers so that each side is completely separate from the other. I think this is pretty smart and cool, because it means that the stuff on the power side can't affect stuff on the control side- in other words a wiring problem on the output side it shouldn't be able to affect the control circuitry. So since I'm unable to easily test the control side without setting up a whole PLC all opened up I have been testing the output, power, side.

And it looks like everything is working as expected. All four of the VN340SP solid state relays switch just fine when I put 24v on the I/O pins. Each pin lights up its own output and none of the other ones. They also don't just power on when 24v is put on the card, which means that the phototransistors in the photocouplers aren't all fused closed or something. I've tried to switch on/off the solid state relays through the photocouplers but with no luck. That's mostly because I'm not sure what the supply voltage they want is for the diode side. I tried to switch the relays through the photocouplers on a working card, but with no luck as well- so I think I'm just not doing something right.

So due to the fact that the output side and control side of the card are not electrically connected and the output side of the card seems to be working fine, I'm thinking the problem lies in the control side of the card. And since the control side of the card is only connected to the PLC through the power/control bus I'm thinking that the PLC must be frying these output cards? 

Does that make sense to anybody? Is it possible for the PLC to be killing my cards?

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Killing just the middle one of the three?  That would be very strange....

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Yeah, that's why I'm confused. Does all my testing check out?

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Posted (edited)

OK so I put the card I was testing into the PLC because it seems fine, and it turns out it was fine. (oops)

I pulled out the other broken card (now the only broken card) and I'm testing it and it looks like all of the phototransistors in the photocouplers are shorted closed and that's why I'm getting these weird results. All of the outputs are high even without power to the control side of the card having power to tell them to go high. 

So I guess I somehow fried all the phototransistors in the photocouplers? Too much voltage / current somehow? Is there a common reason why this would happen?

Edited by furnaceRP

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