[Help!] Analog readings go crazy!

[GuyM142]

Hey everyone,
This year our robot uses 2 potentiometers and today after a defense cross both of them started jumping between readings like crazy with no pattern.
We had this problem before and the last time it happened because of a badly connected micro-switch which caused this problem when it was pressed.
This time we have disconnected all of the DIOs but it didn't help.
We tested the potentiometers' resistance and they work just fine...

We compete tomorrow and we worry that the same problem might occur on our competition robot.
What may cause it? Please help us.
Thank you.

[kiettyyyy]

Sounds like a poor electrical connection. I'd check if your connectors are seated properly, connectors crimped properly and if there are any breaks in the wire.

[GuyM142]

Originally Posted by kiettyyyy

Sounds like a poor electrical connection. I'd check if your connectors are seated properly, connectors crimped properly and if there are any breaks in the wire.

We checked and the readings actually jump from 0 to 1 (minimum to maximum) and even if the potentiometers aren't connected.

Any idea what it is?

[rich2202]

Originally Posted by GuyM142

We checked and the readings actually jump from 0 to 1 (minimum to maximum) and even if the potentiometers aren't connected.

Any idea what it is?

The status of the AIO port is undefined when nothing is connected. You need a connection to pull the port to a steady voltage.

Post a wiring diagram.

[Landonh12]

You could have a short on one of your analog devices. We had this problem and traced it to some bad soldering and insulation by one of the students on one of our potentiometers. The black and red wires were touching underneath a big glob of electrical tape.

Check all of your connections.

[RufflesRidge]

As others have noted, I would check the wiring carefully for shorts or open circuit. I would also check the roboRIO power light and DS power tab for 5V faults (they may also show up in the DS log, I'm not sure). It may be that metal debris in one of the connectors or inside the roboRIO case or a short on a different sensor is taking down your whole 5V rail which would cause the described symptoms.

[Fletch1373]

I'm a little late here, but wanted to add my 2 cents anyway.

If your potentiameter is a single-turn(i.e. 210 or 360 degree) pot, then look for damage to the device. If it's a 360 model and turns past it's range, it may make contact with the other side and read the opposite value. We had this happen when our arm went too far in testing. It essentially pushed the pot housing apart a little, letting it spin freely. Resetting it to within it's valid range and tightening the housing down again fixes the issue.