M1 KP2 Wiegand Interface Problem

[nitewind]

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.

 

[Del91574]

While it's not an explanation, I have had readers stop working on large access integrations that were powered from a different source and the common negative was dicey.
 
Not sure if you have the means, but have you been able to see a raw data of W26 come across out of the unit when connected to the KP2? It may be as simple as some of the bits are getting scrambled or not passing correctly (this sort of issue will drive you insane).
 
If you have means to view raw data, then I'd see what the raw data is and then start plugging it into the hex/dec calculator in windows and get the start/stop and data bits. Could even be as simple as a card format issue....what's the back story on the credential? HID? How is the FC and card # referenced by the credential?

 

[RAL]

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.

 
I'm not sure if there are any internal circuitry differences between the KP and KP2, or whether they are the same hardware design and just packaged differently.  But let's assume for the moment that there is some difference between them.
 
It's possible that the data pulse widths generated by your original reader are on the narrow side, but the KP is able to detect them despite this, while the KP2 is not able to.  The second reader might be generating slightly wider pulses that both keypads are able to detect.
 
This is where it would be really nice to hook up a scope to the data lines and look at the differences between what the two readers are generating.  If you see a difference, that could very well explain it.

 

[Del91574]

Lots of differences between the KP and KP2, including the board.  KP2 is a close cousin to the KP3 off the top of my head, believe they share a circuit board. A few major differences in hardware design, but major components are the same.
 
Been a while since I put in a KP2 or KP3. What they lack in comparison to a KP usually is the reason why they don't sell in my area. Only reason why people get the KP2 is they have a notion the flush mount kit and footprint is nicer than a KP (but I digress about the exposed buttons and smaller display and lacking the thermistor and F-keys...some people would rather have a flush unit)

 

[tmbrown97]

of course you could always try a KAM to hook the reader up to; although since you can't enroll from a KAM it's not my favorite solution... but if you can enroll from a KP elsewhere then hook the reader up to the KAM maybe that'd get this closed out.

 

[homejones]

I haven't read through the entire thread, but I had A LOT of communication issues between my Weigand keypad and my KP2. All issues were resolved once I used 18-2 shielded wire to carry the data between the KP2 and the keypad. In addition, I swapped out the existing Cat5 cable that ran from my Elk to the KP2 with a shielded Cat5. All problems were resolved with the shielded cables.

 

[Del91574]

Can't say I've mirrored the same, but then again, all the reader installs I've done I've either used Northern cable (18/6 OAS) or composite access cable (22/6 OAS for reader) but I've never connected the drain to any ground point.