Compressor/Spike Default Setting = On

Technical Pneumatics
1

This may be a strange time to post this, but on the weekend before our trip to WPI, anxiety over potential problems is starting to build up.

We’ve been having this “problem” for most of the season, although we’re not even sure it’s a problem. It involves electronics and programming, but because it only relates to the compressor, I’m posting this here.

To get to the point, whenever the robot is turned on, or when we are building code, or whenever the cRio is not communicating with the robot, the compressor turns on. We’ve concluded that this is the behaviour of the spike, as its default setting is power on.

This isn’t a major problem, as most of the time our pneumatics system won’t reach 120 psi in the short time the cRio isn’t on if we start with an empty tank. But during code deployment, and if we want to enter the field with an already pressured pneumatics system, it’s kind of a pain to have to keep the release valve open and remember to close it before the game starts.

I’m hoping there is a real quick fix for this, and that it isn’t a safety issue worthy of disqualifying our robot. Thanks.

2

When the robot is powered on, even not enabled, your Spike outputs 12V?

How do you have

A: Your Spike wired.
B: Your compressor power wired.
C: The PWM cable to your Spike to IO board wired.
D: The pressure switch wired.
E: Your code setup.

Also, there is nothing wrong with storing at 120PSI. Especially since the blowoff valve blows at like 125 anyway.

3

This is absolutely definitely not the default setting of anything.

Please be sure that the PWM cable from the spike controlling the compressor is plugged into a RELAY output of the DSC. I have never tried it, but plugging into either a PWM or DIO should connect +5V to the REV (B) pin of the spike leading to your observed behavior.

Refer to this document and this document and this document.

Regards,

Mike

4

First, I do not know of a robot inspector who will allow this to pass.

Second, the PRV is a backup protection to your wiring and code (which must be demonstrated to the inspector) and not a primary protection.

Third, with the compressor running all the time, it is gonna get really hot and fail…

JMHO,

Mike

5

I’ll have to check with a teammate, but I think we may have wired the Compressor Spike to the DIO instead of the relay.

That might explain it. Thanks.

6

The Spike should go to a Relay. The switch on the compressor should go to a DIO. Your code tells your compressor object what DIO and Relay you are on.

Mike-

Perhaps I should rephrase that.

There isn’t anything wrong with going over 120, especially when you are trying to figure out why something isn’t working.

And for storing at 120, you are allowed to. All your working pressure has to be 60 or below though.

As to always having the compressor on-

I dunno. Last year our compressor was pretty much running the whole time. (Before a match, during a match, during testing) and it never failed us.

Our T-Shirt cannon robot also used 2 compressors and were constantly running, operating from 80-130 PSI.