power draw allowed on solenoid breakout

[Bruceb]

So the manual says that if I have a 4 port crio the maximum power I can draw from the solenoid breakout is 21w. Does it matter if that is all from one set of pins or is there a limit to how much I can draw from a pair of pins?
We are running 4 valves that draw 3w each and want to wire them all to the same set of pins to be controlled all at once.
12W at 24V is .5A Can a set of pins handle 500mA?

[Bruceb]

Never mind. I found my answer here
http://www.usfirst.org/sites/default...20Breakout.pdf

A set of pins has a max current of .75A.

Thanks

[FrankJ]

By rule (R51) you can only hook up one solenoid per output. So in this case can & may means two different things.

[Andy A.]

As Frank pointed out there is a legal issue here.

<R51> Each power regulating device may control electrical loads per Table 4-4. Unless otherwise noted, each power regulating device may control one and only one electrical load.

As I read it the rules are a little fuzzy, though. This is sort of lawyering but, because the breakout isn't exempted from the 'one and only one electrical load' part, strictly speaking <R51> would preclude attaching more than one solenoid (or any electrical load) to each breakout board. We know this not the intent or common interpretation, and the addition of the solenoid module/breakout board as a power regulating device wasn't made till the Valentines day team update. The table should probably make a specific allowance that the breakout board can control one load per channel and/or specify a maximum load for each channel. Note that <R69> already defines the maxium cumaltive load when powered by the 24v supply (16 or 21 watts, depending on C-rio type).

In any case, there's not much advantage in ganging multiple solenoids to one channel. Enabling multiple channels on the breakout board at the same time is trivial to do in programming and gives you far more flexibility. If you're out of outputs on the breakout you're also probably pushing the wattage limit defined in <R69>; not great for legal and technical reasons.

If you really want to run multiple solenoids off a single 'output', you can gang multiple pneumatic relays off a single Spike relay. This requires the use of 12v solenoids, obviously, but it is explicitly allowed for in the rules.

[Bruceb]

Hoping Big Al chimes in here but the issue is running out of ports. THe cumulative draw is no where near the 21W limit however.
We could add another 24V solenoid breakout but we really didn't want to.
If we use a spike and four 24V solenoids we could put connect them in 2S2P and this would also work I think.

[Mark McLeod]

We can only have a single 24v solenoid breakout per the R42 rule.
We can have more 12v solenoid breakouts.

The Spikes can be used for 12v solenoids, but not for 24v.
They aren't rated for that.

[Bruceb]

Dang
Thanks

[Bruceb]

ya the spikes are out I was thinking backwards on the voltages.
Thanks again

[FrankJ]

The rules actually say you can only power one solenoid breakout from the PD 24 supply. The question becomes can you use a custom circuit to power the second solenoid breakout at 24 V. Al was checking on that from another thread.

[cgmv123]

Originally Posted by FrankJ

The question becomes can you use a custom circuit to power the second solenoid breakout at 24 V. Al was checking on that from another thread.

Q237b says you can't.