Using Arduino relays

I’ve read the rules several times to understand this, but I’d like a second opinion. We are out of Pneumatic Solenoid outputs.

Originally I was going to use Arduino relays to run a couple more pneumatic solenoids. They would be connected to the relay outputs on the roborio and powered from the VRM 12V 500MA rail, but it appears that will not be legal because of the way the rules are written.

Am I right in thinking I HAVE to use Spike relays?

My reading agrees that no other relays are legal.

However you could also get another PCM and connect it to a main PDP slot.

Right about that, except we have no PDP slots left. So my next question is this - I can’t see anywhere that forces me to power the pneumatic control module from the PDP. Can I power it from the VRM?

Each PCM’s solenoid current is 500 mA:’s%20Guide.pdf

Each VRM can output up to 12V 2A:’s%20Guide.pdf

As long as the compressor was ab-so-freakin-lutely hooked to the other PCM, I can’t find another rule that prohibits this arrangement.

(Though you could also use a splice like lever nuts to make this connection too.)

According to the documentation, the sum of ALL pneumatic solenoid channels on the PCM are 500ma. If you turned on all at the same time. So I think this is the arrangement I’m going to use.

There are places that imply that extra PCMs must be powered off the PDP, such as mentioning that they need breakers, and allowing multiple per terminal.

You may want to get a Q&A ruling on that configuration.

R47 says all circuits must be powered by the PD board. You can power one PCM off the PCM terminals on the end of the PD board (R54). That fuse is also used for the radio so I think it is a bad idea to power the PCM with a compressor on it as well, You allowed one PCM per breaker per R58. The way I read all this is you cannot power the PCM from a VCM.

Yeah, I had a very meticulous team mentor look through the rules and hit on 47 as well. This is very frustrating. 16 PDP outputs is simply not enough.

I think you could use the old KOP “Spike” relays, every established team has a box overflowing with them. [Youngsters: we ran pneumatic solenoids with Spikes in the IFI, pre-cRIO era.] Check the rules, you may be able to branch several from one PD port, of which you have zero spare unfortunately. And control the Spikes from the four roboRIO relay outputs.

You’ve probably already ruled this out, but are any of your motors eligible for sharing pdp slots? That could free one up for the second pcm.

Edit: scratch that sorry. Went to reread the rules.

Can you remove a function anywhere? If you can replace a motor with pneumatics then you could free up a slot.