Digital Inputs and the Digital Side Car

[BlueDevilFRC]

For the past few days our team has been working on trying to get a simple limit switch to work to no avail. We have tried completing the circuit with two wires, but that did not give us any input back either.

We are programming in labview and we have a very simple code set-up, so we do not believe that it is the problem there, but we are not sure at all. We have tried with PWM and relays on the sidecar and these outputs all work fine.

Our indicator on labview continuously displays an output of 0, both when the limit switch is pressed and when it is not pressed.

Does anybody have any idea as to why nothing is happening?

Thank You,

Included are pictures of the circuit/sidecar and the programming on labview.

[RyanN]

Unfortunately, everything looks correct.

The digital inputs work using an internal pullup resistor, an 10K resistor to be precise, in the digital sidecar.

Have you hooked power to the DSC? I'm not sure if the control system is powered on or off in the picture, but it appears to be off. Without power to the DSC, the pullup resistors won't work, and therefore, your output will always be 0.

Next, it's possible, but unlikely, that the limit switch is shorting out. Have you tried to unplug it while running the code. With nothing connected, it should output a HIGH due to the pullup resistor.

Next, try a different port. We had a port go bad for no reason in 2011 right before our unveiling. It was a very familiar scenario. Simply move the limit switch to a different port, or get a new DSC.

[MagiChau]

The PWM cable appears to be connected to the DSC reversed. The Brown wire connected to COM should go to signal. The Yellow wire connected to NO should go to (-)

[BlueDevilFRC]

Thank you for the reply, sadly we already tried most of what you suggested.

The sidecar was currently off when taking pictures, but all the lights were all on when testing.

We have tried multiple limit switches, and have tried directly connecting the ground wire and the signal wire on the DSC.

We have also tried using ports 1, 4, 5, and 8 on this sidecar and another, which all resulted in the same thing, nothing.

[MrRoboSteve]

I see you have a ribbon cable -- is it from 2012? There was a known issue with cables from that era being put together backwards, which could cause this issue.

[BlueDevilFRC]

We replaced the ribbon cable and it worked, thank you for all the help.