I purchased a simple W26 card reader/keyboard, hooked it up to the KP2, and it works great for programming, arming/disarming and access control. I checked the idle voltage of this reader's D0/D1 outputs to GND, and it's only 4.2V, so that rules out a low output voltage issue with my original print/card reader. However, that still doesn't explain why my print/card reader works with my M1KP, but not my KP2.
It would appear that the KP2 is working fine, since the new reader works with it. However, by the same logic, it would appear that the print/card reader is working fine, since it works with the M1KP. I'm not sure what to try next.
It would appear that the KP2 is working fine, since the new reader works with it. However, by the same logic, it would appear that the print/card reader is working fine, since it works with the M1KP. I'm not sure what to try next.