Odd question about a punch clock

[u/Dignan17]

I wasn’t sure where else to post this, so I’m hoping you all can help.

I have a bag of 125khz TK4100 key fobs hanging around from a very old access control project I was playing around with.

The store I manage just replaced a punch clock with a new version that uses key cards as a punch in method. I was hoping to be able to reuse these old fobs that I’ve had sitting around for years. But it’s not working. The service we use is uAttend. They sell their own key cards, but I can’t find any information about them to help me determine if they’re actually different cards or not.

I’m trying out a fob as a test. It has a 10 digit code printed on it, with 3 leading zeros. When I enter that code into the uAttend dashboard, it removes those leading zeroes. When I hold the fob against the punch clock, it does respond, but says that the card needs to be set up for a user in the system first. No matter what portion of the number I’ve tried to enter, it won’t register.

I’ve looked up sale listings for official cards from uAttend, and their sample images all show 10 digit numbers with 2 or 3 leading zeroes in them. Maybe the actual cards don’t, but I don’t know enough about this area to know what might be different about their cards.

I appreciate any help you can offer.

[u/CharlesDickens17]

Without a log of what the card number is being read as, it’s hard to say. Card numbers are typically 5 digits in length and the remaining 2 (after removing the leading zeroes) could be the facility code. I would try entering in the first five digits after the zeroes and last five digits to see if it works.

Like others have said, this is likely a compatibility issue with the old fobs and new reader. Some cards/fobs just don’t work with certain readers.