[Help] Problems with Encoders and PID Control

[xNovax]

I have run into an issue with an encoder on my teams robot, the encoder was working fine at the beginning of the day but as the day went on the encoder stopped working. Now we cannot get any encoders to work on the robot. Here is what we have tried: Replace the encoder with a new one, change the wire connection to the encoder, changing the DIO port for the encoder, triple checking our code, testing the DIO ports with a limit switch(successful) and power cycling the robot and our drive station.

I have become stumped with what is causing the issue. My mentors seem to think that it is something to do with software but I have checked the code multiple times.

Here is our code: https://github.com/Cyberfalcons/robot2015

Here is the class where the encoder is being used: https://github.com/Cyberfalcons/robo...nElevator.java

Any help is greatly appreciated!

[cjl2625]

I once had a similar problem where I couldn't get a reading out of our lift encoder. It turned out that the limit switch at the bottom was constantly on, so the encoder kept getting reset to zero.
I see this in your code, which looked similar to what I was doing:

else if (getBottom() == true) {
			resetEncoder();

Just an idea

[xNovax]

That should only cause problems if we try to go down when the limit switch is engaged. We have tried hand spinning an encoder that is not attached to any subsystems and it still does not read anything but 0.

[Thad House]

Originally Posted by xNovax

That should only cause problems if we try to go down when the limit switch is engaged. We have tried hand spinning an encoder that is not attached to any subsystems and it still does not read anything but 0.

Remember all DIOs return true if nothing is attached to them. So if the limit switch came unplugged or went bad, the encoder would be constantly resetting. So if you were trying to test the encoders but had all other DIOs unplugged, the encoder would constantly be getting reset, unless you commented out the reset code.

[xNovax]

We tested the limit switches to make sure they were working before we started messing with other stuff.

[Ether]

Originally Posted by xNovax

That should only cause problems if we try to go down when the limit switch is engaged. We have tried hand spinning an encoder that is not attached to any subsystems and it still does not read anything but 0.

Time to get out the voltmeter.

[xNovax]

Originally Posted by Ether

Time to get out the voltmeter.

We checked the connections in both of the wires we tested with.

[Ether]

Originally Posted by xNovax

We checked the connections in both of the wires we tested with.

How did you check them?

[xNovax]

Originally Posted by Ether

How did you check them?

Beep test (Sorry I don't know the technical term)

[Ether]

Originally Posted by xNovax

Beep test (Sorry I don't know the technical term)

What's a beep test?

[E Dawg]

Originally Posted by Ether

What's a beep test?

It's a continuity test, I believe.

[Ether]

Originally Posted by E Dawg

It's a continuity test, I believe.

You can't measure volts with a continuity tester.

[jbernardis]

Originally Posted by xNovax

Beep test (Sorry I don't know the technical term)

A simple continuity test is not enough for a cable. You also need to check the cable for short circuits - a cable with a short can and often does show continuity on each wire.

Our team learned this the hard way.

[E Dawg]

Make sure that there are no electrical issues anywhere else on the bot, as well. That has caused issues for us even though it wasn't directly connected to the sensor.

[Hoover]

This is rather urgent...

Did you ever find the problem with this? This started happening to us and it is wasting all our enbagging time.

We tried 3 different encoders
We have verified they are spinning
We tried different digital ports

We rolled back code to where we knew it worked.

We recently updated the firmware to the roborio as required. Other than that, we should be in the same state we were when it was working.

The problem sounds so similar to the one described in this thread I wonder if it is the same problem.