Encoder Conundrum

[Hitchhiker 42]

So, our team has had season-long difficulties with our encoders on our drive train (This one).

Consistently, at first, we had our left encoder working and the right one not working. We worked around this, using only the left side for distance. However, we decided to fix this in the off-season. We replaced both encoders (left & right) for brand new ones. We also tested the wires for shorts and continuity where they should/shouldn't be. All fine. The problem persists.

Our next step was to try to connect them directly through the Talon SRX with the little expansion board for wire --> ribbon cable. Now, the right encoder started working and the left one didn't. Thinking this was the wires, we replaced & tested all four parts (2 ribbon cables & 2 encoder wires). No difference. The problem persists with the left side now.

We are going to try to switch to magnetic encoders, but it's still an interesting conundrum as to why all of this happened. Why was one working, and then they switched?

Any advice is helpful, Thanks!

[GeeTwo]

Originally Posted by Hitchhiker 42

We are going to try to switch to magnetic encoders, but it's still an interesting conundrum as to why all of this happened. Why was one working, and then they switched?

Any advice is helpful, Thanks!

I don't see enough information to make a likely call. If you have access to an oscilloscope, My first recommendation would be to look at the output of the two encoder channels (relative to signal ground) vs time. Do you get a good quadrature signal? (I'm assuming quadrature encoders; most of the ones used in FRC are.)

If you do not have access to an o-scope, try swapping the Talon SRXs - move both the power wires to the motors and the encoder cable, and program the channels as swapped (unless you want to re-address the Talons). If the problem follows the encoder/cable, the problem is likely there. If it follows the talon, then I would suspect a software issue, though it is possible that something is wrong with that talon.

[page2067]

So many complain over those encoders - but we used them from 2009 through 2015 with generally good results. yes sometimes not, these were usually due to either 1) contamination/ scratches of the metal optical target, or 2) associated with the connector, usually after an attempt to unplug and replug the connector - a delicate operation to be avoided.
they are a little fussy, prompting many to shift to other options (including us last year, not necessarily just the magnetic encoders, some go for Grayhill 63R's and another is the AM CIMcoder), but once they are set right up, they work fine. We still have some in inventory, so will use them at some point.

[euhlmann]

This probably isn't it, but make sure the ribbon cables are plugged in the right way on both sides. We had this issue during build season