This may be a dumb question but is it possible to have the pressure senor turn on and shut off at different values. We have 5 airtanks on the robot and the switch is currently set up to shut the compressor off at 115 psi on the high pressure side but when we actuate anything that uses even a little air the switch kicks the compressor back on to get to 115 again. We were thinking maybe to set it to kick the compressor on at 90 and then stop at 115 again. We were hoping to add more tanks and store most of the air we needed for a match and then if the compressor had to kick on near the end of the match that would be ok but not the whole match as the compressor sucks a lot of battery and can lead to brown outs. Open to ideas thanks in advance.
If using a analog pressure sensor, you can get the value in code and use that to manually toggle the compressor (well, toggle whether it’s enabled or not, you can’t use this to bypass the safety feature of disabling at ~120psi)
Edit: analog, not digital
but we could set it so that it wouldn’t kick on until it hits lets say 90pisi?
This is the pressure switch we have
That pressure switch isn’t configurable at all. If you want to have a specific (lower) pressure to enable at, you would need a sensor that can tell you the actual pressure. REV sells an analog pressure sensor that would work for this. Then its just up to your code.
that will just shut it off at 115-120. You need one of these.
The other question is why 4 tanks?
You will need an analog pressure sensor (in addition to the digital pressure switch of using the CTRE PCM) Something like this would work: https://www.andymark.com/products/analog-pressure-sensor
R805C states that you must use the analog and/or digital sensor. The digital sensor is not required if you are using the analog one. The Pneumatic Hub can be configured to use just digital, just analog, or both in a hybrid mode.
Ahh, didn’t know that, good to know!
With the REV Pneumatics Hub that is true. However with the old CTRE PCM you can use an analog pressure switch plugged into a RIO and do the same thing. You just also need the digital pressure switch plugged into the PCM.
we plan on adding more tanks but the problem is the same no matter the amount I think?
So if we have the CTRE PCM we need both and analog switch and a digital switch?
No, you can plug the REV Analog Pressure Sensor into the RIO
Edit: I am mistaken, you need the REV Pneumatics hub to be able to only use the REV Analog Pressure Sensor, so yes, you will need to use both. I don’t know if in code you will still be able to configure the on and off depending on your PSI but you should be able to.
That does not satisfy R812. If using the CTRE PCM you need the pressure switch.
ya, I just realized that. I posted an edit
This talks about using the analog and how to implement it in your code. I also put up some pneumatics lesson content here on frczero.org and that is briefly talked about in 5.5. I’m planning to add more details but if you let us know how your controls method works I’d like to add the concept to the knowledge base.
4 is already a lot of tanks.
have yo used this calculator to asses your needs?
We are trying to use almost all stored energy and then if the compressor needs to kick on towards the end of the match that ok. We are just trying not to have the compressor run all match since it drains the battery quickly
Follow-up question: can you measure the rate pressure is dropping with the REV sensor, and have the compressor kick on preemptively before you hit your low pressure number?
Meaning, it normally just kicks on at 90 and off it at 120, but say you’re doing multiple things and it’s dropping toward 90 but very quickly, can you configure that in code?
Probably with math and if/else statements. I’m no programmer but I feel like it is possible