Originally Posted by
the_gentlegiant
Every button on your control will flip a bit in a parameter or data table somewhere. If you're working with a membrane keypad they're certainly not as easy to troubleshoot with a volt meter as an old wired up switch would be.
Anyway, back to the control. Somewhere in the manuals there will be an address map for all the keys. I think you look in the diagnostic tables on the control for the bits to move. If you have no manuals, you can do it the hard way by pressing a known working key close to the one that doesn't work and watch the screen for a corresponding bit flipping from zero to one and back. (You might have to page through many screens.) Once you find that, you can hope your iffy key is in the same byte row or at least close to it.
In short what I'm trying to say is use the visual bit movement to verify the operation of the key. If it's working every single time in the bit display but still not making the machine operate accordingly , then at least you've eliminated the keypad as your problem and can look elsewhere. Meaning bad connections, wet cables or connectors, loose connections, etc. Both on motors and in the control cabinet.