AC/DC Outputs on same card. OK to do so?

The card is capable of both AC/DC output signals. I would like to segregate and use one half of the outputs (8) for AC signals for toggling solenoid valves, and the other half of the card (8 outputs) for DC signals to turn on/off Ice cube relays. All solenoids are under 2A devices and module supports 2A per point. Is it OK to do so as in mix AC/DC on the same card. I have not seen anyone do this before but was curios.



Thanks

Depends on the card.

Some relay output cards are isolated relay outputs - that is, each output has two connections, one for each side of the relay.

Others simply have a single common for all relay outputs and then each output has a single connection for the other side of the relay.

Others still are split into two isolated groups, with two commons, each serving half the output relays. Based on your description, I'd hazard a guess that this is they type of card you have, but you don't specify or provide any part numbers, so it's best to spell it all out to be sure.

If you do have the latter type of output card (or the first type - just not the second), then yes, you could do it. But "could" is not really a ringing endorsement. I've never seen it done before either, and would not do it myself unless I really had no other choice. The risks of a mistake during wiring/troubleshooting/etc, and the consequences thereof, are just too high. You can do it. But personally, I wouldn't.

I've put it like this before: there's no law against riding an electric scooter down a waterslide.

as already stated, depends on the card.
What type of card is it? brand and model #
james

You can do, yes. again, depending on the card.
You should not do it, as it is a problem just lurking.
When I was working at a dairy, our raw receiving bay was down for three days, because of this exact scenario, which lead to bricking a complete PLC rack.
It is doable, but it's not advisable.

I have - For home use, not industrial - used a single common relay output to control both Ac & DC by controlling the neutral/0V side, with the 0V output of the DC power supply bonded to the neutral.



I also have wired a DC sink output card similarly using 24V from a power supply and 12V from my solar battery bank with the 0V's bonded together.


I also have wired a DC source output using 24 and 12 volts with the commons NOT tied together.


As long as you don't create an unwanted current loop it works.


Also, if you don't have the 24V AC/DC input card you can run 24VAC to inputs and put a power diode on the common that will give DC to all inputs. When you do this you have to make sure the component providing the AC signal will work on DC. Some AC devices will work if the output is rectified to DC and some will not. 2 wire AC (AC only) proxy's generally will not.

Strictly speaking, it would work. I've seen it done, but I'd never design or build a panel wired that way. It's an invitation to confusion for anyone who has to work on the system later.

skyfox said:

The card is capable of both AC/DC output signals. I would like to segregate and use one half of the outputs (8) for AC signals for toggling solenoid valves, and the other half of the card (8 outputs) for DC signals to turn on/off Ice cube relays. All solenoids are under 2A devices and module supports 2A per point. Is it OK to do so as in mix AC/DC on the same card. I have not seen anyone do this before but was curios.



Thanks

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I'd strongly consider using interposing relays (and good flyback protection) on your solenoids. Ice cube relays are much cheaper to replace than PLC cards when the inductive kick eventually trashes the relay contacts. This approach also solves your mixed voltage issue at the PLC card.


-rpoet

rpoet said:

i'd strongly consider using interposing relays (and good flyback protection) on your solenoids. Ice cube relays are much cheaper to replace than plc cards when the inductive kick eventually trashes the relay contacts. This approach also solves your mixed voltage issue at the plc card.


-rpoet

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+1