To wire up our double solenoids in past years we’ve followed the double diode trick found in the robot manual from 2003. It roughly sketches out that you take the gound leads from the solenoids and connect them together and hook them up to one side of a SPIKE (M-). Then attach a diode to one solenoid +V lead and attach another diode reversed to the other solenoid +V lead. Finally connect the ends of the diode together and attach to the other side of the SPIKE (M+). It seems to work, but we’ve encountered problems with the solenoids after a while. Does this diode trick work as I described?
It seems to me that it should take 4 diodes to ensure the polarity on the solenoid.
I heard that some teams connect the two ground leads from the solenoid directly to ground on the Fuse Panel and wire just the +V leads (separately with reversed diodes) to the SPIKE. So I’m wondering, how do other teams wire up the double solenoid to work off of one SPIKE?
I think that we just ran all of our negative leads from solenoids to ground, then hooked the positive leads to the spikes. So with one double solenoid you would run both negatives to ground, then connect the positive sides to opposite sides of the spike. Then by putting the spike one way you can make it go one way, then putting it the other you make it go the other.
Disclaimer: That is what I think we did. I helped wire it last year and I remember for sure that there were no diodes anywhere, and we have not had any problem with it ever, but I dont remember if that was exactly what we did.
Just don’t forget that it is possible to run a SPIKE in both forward and reverse at the same time (both M- and M+ are raised to +12V). If you run your ground straight to your breaker panel, and your solenoid power leads to M+ and M-, it IS possible to energize both sides of your double solenoid at the same time. Be sure to shut one side off as you turn on the other explicitly.
a ram? a cylinder you mean? if so then no. a constant power to a solenoid will not multiposition a cylinder. never knew you could power both sides of a spike at once. interesting. ive tried both ground and diode ways. i personally liked the two separate circuits (ground) method better.
another way is to just connect the two opposite. so one side is positive but for the other solenoid on the same valve is neg. and the opposite on the other side of the spike.
If you use a double solenoid, the cylinder will maintain its’ position (open or closed / extended or retracted) when power is shut off to the robot because it takes power to move the solenoid to the other position. So, yes, it will keep the ‘ram’ positioned.
Single solenoids return to their normal position when power is shut off so the cylinder will not maintain its’ position.
I assume you are not talking about multi-positioning (stoping mid-way).
What happens if you apply power to both sides of a double solenoid at the same time…? Will apply pressure to both sides, or vent both sides (or both?) or will it just go to whichever side it thinks got power last?
On past robots we used special female spade terminals that have a male spade sticking from the back of the connector and connected both the ground wires from double solenoids to that spade connector. It is just like connecting to the ground terminals on the breaker panel but you may have to argue with the inspector because for some reason they did not like it but it was still aloud at both are regional and at championship last year.
If you apply power to both sides, you cannot really know which way the solenoid will go. With all the variables (timing of the same time, actual power level, tolerances in the solenoid, etc.) it is a guess.
In the 2004 Programming reference guide on page 21 depicts an example
of “Solenoid Digital Outputs.” Does code need to be added to use the
4-way valve [given in the kit] sucessfully with two pistons for the
arm. If so would someone mind sharing their code? Is this functionality in the 2005 FRC_default.hex file?
Referencing the full-size RC reference guide p.7, I assume that I can
use pin numbers 2,7,10,14, on the OI–wired to a spike relay to
control solenoids of pneumatics, which is what it sounds like people are saying here. Anyone have a picture of this completed?
After looking at the code -right now at least, I’m not seeing where the
signal is coming from to open/close the solenoid for a pneumatics
system.
Just to clarify, a cylinder hooked up to a single solenoid valve has a “home” position (which will be either extended or retracted, depending upon how you tube it up).
A cylinder that is in it’s home position when the power is cut will stay in that home position (which means it will maintain that position).
A cylinder that is not in it’s home position when the power is cut will return to it’s home position (which means it will not maintain that position).
Here’s a picture of how our team did this. It’s not perfect and was done in paint, but that’s what I got. We did this, so there’s no need to run a separate wire to the ground on the circuit board
