Encoder issues

[Thad House]

We are trying to set up our encoders for autonomous, and we are having a lot of trouble. when we are rotating the encoder 1 full rotation, the programming is reporting only a 250 degree rotation, which is causing a lot of problems. Also, we are trying to use the encoder to correct for drift, which is also a large problem. it will not work, and now it is rotating the robot without moving forward.
Any help fixing these issues would be helpful.

[EricVanWyk]

The encoders report counts/ticks, not degrees. Different encoders will have different counts per revolution. I'm betting you have a 250CPR encoder.

[Thad House]

we are checking to see if we ordered 250 cpr encoders

[AllenGregoryIV]

If they are encoders from AndyMark look at the packaging. I believe the 250 count encoders are marked as such. We had 3 360 count and one 250 count on our robot. It was really confusing for a while till we figured out the problem.

[Alan Anderson]

The other confusing thing is that the E4P encoders from US Digital have two different three-digit sections in the part number. One of them is usually 250, meaning its code disk is meant to press on a quarter-inch shaft. It's the other section that you need to be looking at to decide whether it's a 250 or 360 count per revolution disk.

I don't know if it's only the code disk that determines the resolution, or if the circuit base differs as well. I think we'll have a chance to find that out, as our practice robot seems to have ended up with 360-count encoders on the drivetrain while our competition 'bot has 250-count ones. We have a couple extra 250-count code disks that can be substituted (if we can get to that part of the robot without taking too much apart).