a ridiculous reset button

[4AngryNutjobs]

Hey guys,
We have a limit switch that is supposed to turn off a motor when pressed. That is, the motor is to run until the our lift descends and hits the switch, stopping the motor. Only problem is that the switch value is always reading true, stopping our motor even before it begins to move. This happens even when the switch is unplugged. Any suggestions as to why our program does this?
Thanks,
Your 4angrynutjobs

[Mark McLeod]

• Switch plugged into the wrong Digital Input - test by jumping the signal to ground (bypassing power) & watching in code
• Switch broken - test with a multi-meter
• Switch wire broken - test at the far end from the switch with multi-meter
• Wrong wires/connections used - visually inspect, two outside Digital Input pins ONLY (Sig & -), no center pin (NOT pwr)
• Code using duplicate Digital Input - test with a different Digital Input
• Digital Sidecar not powered correctly - check for three brightly glowing power indicators

[Alan Anderson]

Originally Posted by 4AngryNutjobs

Only problem is that the switch value is always reading true, stopping our motor even before it begins to move. This happens even when the switch is unplugged. Any suggestions as to why our program does this?

If you describe what kind of switch it is and how you have it wired, we can help you better.

A typical limit switch for this application should be wired between the (-) and (signal) pins of a Digital Input. The input will indeed always read true with nothing connected, or with the switch open. It will only read false when the switch is closed.

[Al Skierkiewicz]

Most likely you have wired the switch such that it is always open. The pullup resistors in the interface will pull up to make that input high all the time. You can try just modifying the code knowing that the input will be high until pressed.