Exhaust in Solenoids

[FRC Team CC]

Originally Posted by Mark McLeod

What model solenoid are you trying to use?

We are using the solenoids from this link: http://www.wcproducts.net/pneumatics.

Originally Posted by Mark McLeod

If you plug the exhaust ports, then the solenoid will cease to work. It only works by letting air out of the cylinder through the exhaust ports.

So we are trying to control a piston that is plugged in to one of the A ports (the solenoid is connected to port 0). It seems that if we don't block off the exhaust, the air tanks don't build up in pressure as all of the air leaks out of the solenoid exhaust. In our current setup, we have our compressor connected to our compressor and a regulator. The regulator is connected to the solenoids. Is something wrong with our setup that would cause this issue?

Originally Posted by ctt956

To maybe fix the leak, try checking the ends of the air tubes, and see if they're cut straight. If they've been cut at an angle, they can leak. Cutting them straight should fix it. Note that this may not be the issue, but it's a simple thing to check before you disassemble the whole pneumatics system. Just make sure to vent any air in the tank before working on anything!

Our air tubes seem to be cut straight, so that shouldn't be an issue, but thanks for letting us know for future reference!

Originally Posted by headlight

A single solenoid should be enough to control both the A and B ports. The important thing is that it is a 4/5 port solenoid.

If there is air leaking out of the exhaust port it is usually either an internal leak in the seal of the air cylinder or a leak in the gasket between the solenoid and the manifold block (if you are using a manifold setup).

Our solenoids are 4 port solenoids. We have a picture attached for what our setup looks like.

Thanks,
Charging Champions

[Owen Busler]

Arent pneumatics not allowed in ftc?

[headlight]

Originally Posted by FTC Team CC

We are using the solenoids from this link: http://www.wcproducts.net/pneumatics.

...

Our solenoids are 4 port solenoids. We have a picture attached for what our setup looks like.

Thanks,
Charging Champions

Looks good. We use that exact same setup on our FRC robot. How bad is the leak? I'm curious about what you have plugged into the B ports on the left side, and why there aren't corresponding tubes in the A ports. Also, are you feeding air into the threaded "P" port on the side of the manifold not shown in that picture?

Can you tell which exhaust the air is leaking out of? EA or EB? If you manually trigger each solenoid, does it switch which port it is leaking out of? This would be a way to narrow down which part of the circuit has the problem.

If I were trying to fix this I would unscrew each solenoid and wipe off the gasket and the mounting surface, then carefully re-mount them, alternately tightening the two screws to reduce the chance of the solenoid sitting crooked. We have also had the rare instance where the solenoid was leaking internally.

[FRC Team CC]

Originally Posted by Owen Busler

Arent pneumatics not allowed in ftc?

We are an FRC team. Its just that the account that we are using right now is the one we used last year when we were an FTC team . Sorry about the confusion.

Originally Posted by headlight

Looks good. We use that exact same setup on our FRC robot. How bad is the leak? I'm curious about what you have plugged into the B ports on the left side, and why there aren't corresponding tubes in the A ports. Also, are you feeding air into the threaded "P" port on the side of the manifold not shown in that picture?

Can you tell which exhaust the air is leaking out of? EA or EB? If you manually trigger each solenoid, does it switch which port it is leaking out of? This would be a way to narrow down which part of the circuit has the problem.

If I were trying to fix this I would unscrew each solenoid and wipe off the gasket and the mounting surface, then carefully re-mount them, alternately tightening the two screws to reduce the chance of the solenoid sitting crooked. We have also had the rare instance where the solenoid was leaking internally.

I'm not exactly sure if there is a leak. It seems that we are only able to control the A ports on the solenoid. We are not able to control the B ports, so the air keeps leaking out of there and makes the A ports useless.

Here is our code. Let us know where we are making a mistake:

package org.usfirst.frc.team6560.robot;

import edu.wpi.first.wpilibj.Compressor;
import edu.wpi.first.wpilibj.IterativeRobot;
import edu.wpi.first.wpilibj.Timer;

import edu.wpi.first.wpilibj.*;
import edu.wpi.first.wpilibj.smartdashboard.SendableChooser;
import edu.wpi.first.wpilibj.smartdashboard.SmartDashboard;

/**
* The VM is configured to automatically run this class, and to call the
* functions corresponding to each mode, as described in the IterativeRobot
* documentation. If you change the name of this class or the package after
* creating this project, you must also update the manifest file in the resource
* directory.
*/
public class Robot extends IterativeRobot {
   static final long TIME = 10000; // ms
   static final int SAMPLE_COMPRESSOR = 0;

   Compressor sample_compressor;
   long m_autoStartTime;
   long m_autoStartTime1;
   long m_autoStartTime2;

   Solenoid solenoid_0;
   Solenoid solenoid_1;
   Solenoid solenoid_2;
   Solenoid solenoid_3;

   public void robotInit() {
       sample_compressor = new Compressor(SAMPLE_COMPRESSOR);
       solenoid_0 = new Solenoid(0);
       solenoid_1 = new Solenoid(1);
       solenoid_2 = new Solenoid(2);
       solenoid_3 = new Solenoid(3);
   }

   public void autonomousInit() {
       m_autoStartTime = System.currentTimeMillis();

   }

   public void autonomousPeriodic() {
	   
	   solenoid_0.set(true);
	   solenoid_1.set(true);
	   solenoid_2.set(true);
	   solenoid_3.set(true);
       
   }

}

Thanks,
Charging Champions

[Mark McLeod]

For a single solenoid
if
solenoid_0.set(true); - seems to be activating your A port (B port off)
then
solenoid_0.set(false); - would switch to activate the B port (A port off)

P.S.
You want to watch what the individual indicator lights are doing on the Pneumatic Control Module (PCM).
If your software works correctly, the status light for each solenoid will be (could be the reverse of this):

• lit=port A deactivated/port B activated
• unlit= port A activated/port B deactivated

And you should be able to see them change as your code changes the solenoid from true to false to true.

Once you are sure your code is doing what it is supposed to be doing, then look at the plumbing on the manifold. But make sure your code is operating correctly first.

[headlight]

Each solenoid only has two states.

State 1: Port A is connected to supply Pressure (P), Port B is connected to Exhaust B (EB).

State 2: Port B is connected to supply Pressure (P), Port A is connected to Exhaust A (EA).

With the solenoids you are using, one of these states will be the default. If you are using air cylinders that are powered in both directions by air you should have tubes running to both A and B ports. If you are using air cylinders that are not powered by air in both directions, then you should plug the unused port. I'm personally a fan of these plugs, but some people like these better. You can also get them from here.

[FRC Team CC]

Originally Posted by Mark McLeod

For a single solenoid
if
solenoid_0.set(true); - seems to be activating your A port (B port off)
then
solenoid_0.set(false); - would switch to activate the B port (A port off)

P.S.
You want to watch what the individual indicator lights are doing on the Pneumatic Control Module (PCM).
If your software works correctly, the status light for each solenoid will be (could be the reverse of this):

• lit=port A deactivated/port B activated
• unlit= port A activated/port B deactivated

And you should be able to see them change as your code changes the solenoid from true to false to true.

Once you are sure your code is doing what it is supposed to be doing, then look at the plumbing on the manifold. But make sure your code is operating correctly first.

Does activated mean open or closed valve?

[Mark McLeod]

Originally Posted by FTC Team CC

Does activated mean open or closed valve?

You can think of the one solenoid as two valves that always do the opposite of each other, or as a single value with two positions.
In one position (deactivated), it is trying to fill one end of a cylinder (let's call it cylinder end A) by sending pressurized air out port A, simultaneously it is trying to empty the other end of the cylinder (let's call it cylinder end B) by releasing the other pressurized end out an exhaust port.

In the opposite position (activated), it reverses the cylinder action by sending pressurized air through port B to fill cylinder end B, while simultaneously emptying cylinder end A by connecting port A to an exhaust port.

[FRC Team CC]

Originally Posted by Mark McLeod

You can think of the one solenoid as two valves that always do the opposite of each other, or as a single value with two positions.
In one position (deactivated), it is trying to fill one end of a cylinder (let's call it cylinder end A) by sending pressurized air out port A, simultaneously it is trying to empty the other end of the cylinder (let's call it cylinder end B) by releasing the other pressurized end out an exhaust port.

In the opposite position (activated), it reverses the cylinder action by sending pressurized air through port B to fill cylinder end B, while simultaneously emptying cylinder end A by connecting port A to an exhaust port.

We tested it out, and we have no control over any of the valves, even though we used the same code mentioned above and the solenoids are lighting up...

[FRC Team CC]

Do we need to manually lock the solenoids to property use it (the lock mechanism is the blue screw)?

[Mark McLeod]

Originally Posted by FTC Team CC

Do we need to manually lock the solenoids to property use it (the lock mechanism is the blue screw)?

No, it must be unlocked to work.
You can temporarily press the blue button to test, but don't twist and lock it.

[headlight]

No, the blue screw is a way to manually activate the solenoid valve. Unless it is pushed down or set in the lock position it shouldn't stop you from controlling it. A picture of your entire setup might be helpful.

Here is a link to the series catalog for your solenoid, it might give you some helpful information. http://content2.smcetech.com/pdf/SY3.5.7.9000.pdf

[FRC Team CC]

Originally Posted by headlight

No, the blue screw is a way to manually activate the solenoid valve. Unless it is pushed down or set in the lock position it shouldn't stop you from controlling it. A picture of your entire setup might be helpful.

Here is a link to the series catalog for your solenoid, it might give you some helpful information. http://content2.smcetech.com/pdf/SY3.5.7.9000.pdf

Here is a picture of our setup:
http://imgur.com/a/Wwh4t

[GeeTwo]

Originally Posted by FTC Team CC

Here is a picture of our setup:

First, though probably not your issue, the CAN bus is not properly terminated. There should either be CAN leading away to the next device (most likely a PDP with the terminator set) or a 120 ohm resistor on the currently empty pins.

I think I've figured out everything up to the pressure regulator. It looks like the output of the regulator is split, with one going to the manifold, another going underneath. Where does that connect?

Trying to work out the black tubing connected to the manifold outputs. I cannot tell if the two inputs to the cylinder are coming from corresponding A/B ports, or adjacent sets of ports.
In any case it appears that you have plumbed the three unused A ports together, and the three unused B ports together. If all three (or four) of the solenoids are in the same position, this shouldn't be a leak, but if any of them is different from the others, you will be in an exhaust condition - pressurized air coming in one branch of the T and right out through another.
If the cylinder is plumbed to different solenoid valves, The only way you can operate it in this setup without dumping air is to switch all four ports at the same time.

The real solution to this problem (more manifold positions than you have separate items to control) is to plug the holes individually (we have some plugs in our shop, but don't know whence they came) or to use a "Blank Station Kit" like Vex's 217-2949 for each unused control. Edit: I see it is also called a blank station kit with the same part number on the WCP link you provided.

Edit2: Found the plugs like we have on MSC.

[bobbysq]

Originally Posted by GeeTwo

The real solution to this problem (more manifold positions than you have separate items to control) is to plug the holes individually (we have some plugs in our shop, but don't know whence they came) or to use a "Blank Station Kit" like Vex's 217-2949 for each unused control. Edit: I see it is also called a blank station kit with the same part number on the WCP link you provided.

Edit2: Found the plugs like we have on MSC.

You can also use smooth polycord of the same diameter as the tube. I don't know if this is any better/worse, but it's what we had on hand when we used pneumatics.