Fans from the PCM?
 

So just to test a fan today my team connected a fan to one of the ports on the PCM, it worked perfectly. My question is would this be competition legal?

Re: Fans from the PCM?
 

Check rule R42. Custom circuits may be controlled by the PCM.

Is there a reason you don't want to hook it into the PDP to have it run continuously?

Re: Fans from the PCM?
 

Strictly speaking, looking at the manual, I can only seem to find fans being powered off motor controller input leads as being explicitly legal (unless I'm blind).

However, the PCM is allowed to power Custom Circuits, so I should think a fan can be legally powered from there. (insert usual caveat that CD isn't definitive)

Re: Fans from the PCM?
 

That is not the intended purpose of the ports, but I don't see anything that makes it illegal.

Remember, the maximum combined output of all the ports is 500 mA. A small fan could draw 90 mA. A large fan can draw 1000 mA or more.

Re: Fans from the PCM?
 

The purpose of that is to make it legal to cool the motor controller with a fan, and to take the power from the motor controller power leads. I don't think it was intended to be limiting.

Re: Fans from the PCM?
 

First off, check that your fan is in the list of allowed fans in the next-to-last row of table 4-1, in R18.
So, fans are considered motors.

Then, check R42 for which loads can be controlled from the PCB. I see solenoid valves, solenoids, and custom circuits, but no motors (other than the compressor).

From a practical standpoint, all of the solenoid ports put together are only rated for 500mA (See the last line of the table at 1.2 of the PCM manual). Only the smallest fans are going to draw less than this and leave you enough capacity to safely use the solenoids.

Re: Fans from the PCM?
 

A CUSTOM CIRCUIT is defined as follows:

As a motor, a fan would not be considered a custom circuit, so it cannot be powered off the PCM.

Re: Fans from the PCM?
 

Fans aren't CUSTOM CIRCUITS per R30. (Fans are listed in R18, since they have integrated motors.)

The easiest way to get an answer would be to ask Q&A: "Are fans considered CUSTOM CIRCUITS for the purposes of R42?"

Re: Fans from the PCM?
 

Per Table 4-1 under R18, it's not clear if a fan is considered a custom circuit or a motor (please check that table to ensure the fan is, in fact, legal).

R55 part D states "Fans may be attached to motor controllers and may be powered from the power input terminals.". As those motor controller input terminals are correctly connected to the PDP terminals, this ruling would imply that connecting fans to the terminals is legal. I'm not aware of any rule that would make it illegal. As a historical note, this hasn't always been in the rules. A long, long time ago it wasn't strictly legal to hook fans up to the inputs of the speed controllers they were on, and the ONLY way to do it was to go through a dedicated 20A breaker (you could have multiple fans per breaker).

For what it's worth, my team has legal fans cooling our compressor hooked up to a 20A breaker.

Re: Fans from the PCM?
 

We have a 120mm fan connected directly to the PCM to cool our compressor as well. The fan does run as long as the robot is turned on. We don't think this is bad because the compressor doesn't stop being hot just because the robot is disabled.

But what if we get to the competition and the inspector interprets the rules that we have to have this on a controller? Then what controller? It seems silly to waste a Talon on something like this. Perhaps a relay instead? Still it has to be turned on via the program so it isn't running when the robot it disabled.

I'd just like to know so I know to have the parts we need at the competition.

Re: Fans from the PCM?
 

Why?

Re: Fans from the PCM?
 

Read the whole paragraph, especially the first sentence, beginning with "But what if".

The bottom line is that the rules really don't provide clear, unambiguous situations on fans. Some places they're in the list of motors, other places, they're not on the list of motors. If I were of such a mind, I could probably put together a rather tight case that there is no legal way to power an electrical fan that is not part of a COTS computing device on an FRC robot, either switched or unswitched.

Perhaps the best solution is to use a paper fan, and drive it with pneumatics.
:ahh:

Re: Fans from the PCM?
 

Maybe we will look into using a spike.

Re: Fans from the PCM?
 

Can you direct connect the fan to the PDB? Do you have to go through a motor controller?

Re: Fans from the PCM?
 

That's the question that I want to do a little more research to see if I can figure out an answer. Since the fan is a MOTOR from the list of allowable MOTORS

then I assume that they are not CUSTOM CIRCUITS.

And "Table 4-4: Legal Power Regulating Device Use" does not list fans, so we don't know what we are allowed to use to power them, whether it's a Motor Controller, Relay Module, direct connection to the PDB, or the PCM or VRM.

A quick search of the Q&A does not show that this question has been asked or answered.

Re: Fans from the PCM?
 

Consider the intent of the 'motors must be connected through controllers' rule. It is there to stop mechanisms from moving when the robot is disabled. It is a safety concern and a game-play concern. Is it dangerous or unfair to allow a cooling fan to remain on when the robot is disabled? No, unless you jam your finger into one, then it stings like crazy. Fans used to cool motor controllers stay on when the robot is disabled, I see no intent in the rules that you prevent a fan from cooling a compressor from running while the robot is disabled.

FWIW we used a fan hard-wired to the PDB last year with no comments from any inspectors.

Re: Fans from the PCM?
 

We did too. But I get to play inspector this year, too....so I'm looking at the rules a bit differently.

Re: Fans from the PCM?
 

Question submitted on directly connecting a fan to the PDB.

Re: Fans from the PCM?
 

What number? Can you link please?

Re: Fans from the PCM?
 

I can agree with this first hand. That hand got into the fan and broke a blade off the fan. Miraculously my hand was fine, but stung a little. The new fan has heavy duty blades so we put hard nylon grill on both sides. Now it is noisy.

Good points above... yet this. Since the fan is noisy I think I will put it on a relay as I had planned. Whatever we do (or don't), we will get the inspector that makes us do it the opposite way we have done it. If yours is opposite us, and you get passed, we will not tell on you. This has been our way for the last few years (and it has indeed happened), we will be ****ed but stoic.

Re: Fans from the PCM?
 

Q367
https://frc-qa.usfirst.org/Question/...tor-controller

FYI: If you go to the Q&A, and hit Search (without changing any of the other fields), the questions will pop up in reverse order (newest questions first).

Re: Fans from the PCM?
 

Is your fan one of the listed fans from R18?

Re: Fans from the PCM?
 

Indeed, it is just helpful to have the link to the Q&A in the thread. So, thanks!

Re: Fans from the PCM?
 

Also note Q368, which is a more general version of the same question.

Re: Fans from the PCM?
 

We don't know where the 120mm fan came from but we've had it since at least 2012. Even if it isn't from FRC, it would be considered part of a "COTS computing device".

It is an available Commercial Off The Shelf item available to everyone. Similar to this one.

http://www.amazon.com/Cooler-Master-...ords=120mm+fan

I am a cynic so I expect grief for it nevertheless.

Re: Fans from the PCM?
 

You should read the answer to Q315 carefully.

Re: Fans from the PCM?
 

If it's this one

http://firstchoicebyandymark.com/fc15-117


then it should be legal, since it is available from FIRST Choice 2015.


A fan removed from a COTS computing device is not legal, according to Q&A 315

Re: Fans from the PCM?
 

Check page 11 of the 2012 KoP Checklist... Is it that fan? Being on a past year's KoP makes it a legal fan.

Re: Fans from the PCM?
 

I don't think so...R18 specifically states it has to be from the 2015 KOP.

Re: Fans from the PCM?
 

The fan rules are surprisingly restrictive this year.

Re: Fans from the PCM?
 

oh wow, I completely missed that.

but... phew! The fans my team used are still available through FIRST Choice!

Re: Fans from the PCM?
 

Yes, but they seem to restrict us to using that big pile of fans we have from past kits of parts. At least that's what it looks like...I haven't looked at all the part numbers yet on the old fans we have.

oh, now I have.

There are the ebmpabst and PABST 412 (small fan that fits the Victor), and ebmpabst 4212 and 4212 12H, and PABST 4212 N/12H (large fans) in the little pile I just looked at.

Same basic part number, different designs over the years, different wire ends on the large fans, some have a connector, some are bare wires.

Re: Fans from the PCM?
 

They all have bare wires once you cut the connector off to do your own attachment :)

Re: Fans from the PCM?
 

Now you are getting me nervous here since there is no 120mm fan in the 2015 KOP.

It is not identical to the 2012 fan picture but since it is a 2012 KOP picture that is irrelevant.

However I was also saying it is a COTS fan.

Should we zip tie a dinky fan to the compressor head and control it with a Talon? Yougottabekiddingme

I suppose it should be asked if a 120mm fan to cool the compressor is legal in Q&A. I signed up for Q&A but haven't been cleared to ask yet.

Re: Fans from the PCM?
 

No, you should zip tie 5 dinky fans to the compressor head and add 5 more talons to your board. You'll get better air flow.

:)

Re: Fans from the PCM?
 

Q&A 315 might be relevant here.

Re: Fans from the PCM?
 

As I mentioned in another post, there is a large fan listed in the 2015 First Choice, so if it's that fan, it should be legal.The fan is listed as

Large 12V fan, Product Number 4412 ML

which seems to be a different number than the older KOP fans I looked at.

Re: Fans from the PCM?
 

LM**O

Comon' folks tell me you are messing with my head! What kind of unfair advantage is there that be so serious it could be a fan? "Sir! You may not compete with that fan. You are disqualified."

Re: Fans from the PCM?
 

Anything containing a motor is not governed by the COTS rules (unless you remove the motor and replace it with a legal motor)

Re: Fans from the PCM?
 

We don't make the rules, we just try to figure out what they allow us to do.

Re: Fans from the PCM?
 

You might be surprised how effective one of the dinky 412 fans is, when placed about an inch from the head of the compressor.

Re: Fans from the PCM?
 

OK, but it isn't in the KOP. Just throwing a little doubt in there, not that there isn't enough of it already.

Re: Fans from the PCM?
 

You could order one of the fans from First Choice, there are plenty left...if you have credits...you'd have to pay postage, though.

Re: Fans from the PCM?
 

We will and we will be ready with parts and programming if we have to change something at the competition. An annoyance but honestly not a big one.

Re: Fans from the PCM?
 

Anyone find out if it is legal to run fans off of the PCM, or VRM?

I'm just looking for a legal, non-motor controller way to power a fan.

Re: Fans from the PCM?
 

Multiple Q&A's on the topic are waiting for responses from the GDC.

Re: Fans from the PCM?
 

FIRST response:

Re: Fans from the PCM?
 

Better late than never, but we already put it on a Spike Relay and it is only on when the robot is enabled. It is a 120mm fan but is the exact one supplied by AndyMark First Choice.