How Proximity Cards Work

A proximity card is a contactless card which can be read without insertion into a card reading device. Because they don’t require a swipe, they can be left in a wallet or purse and still serve their purpose. Prox cards look the same as the typical 30 mil PVC card but they have an embedded metallic antenna coil inside which hold the encoded data. However, other proximity products include clamshell cards, key fobs and stickers.

How do proximity cards work?

A proximity card is a contactless card which can be read without insertion into a card reading device. Because they don’t require a swipe, they can be left in a wallet or purse and still serve their purpose. Prox cards use a low 125 kHz radio frequency to transmit to a door access reader. When the card is placed on the reader, the card’s unique strand of numbers is passed to the access control panel, which verifies if the number matches an approved number in the internal database. If the card number is approved, the door will be unlocked.

The science behind the scenes:

Bit Formats – There are a number of bit formats that can be used, for example: 26, 32, 34, 35 and up to 40. The important thing to know is that 26bit is the standard (Wiegand) while others are brand specific. Brand specific, or closed formats, are not any more secure, they are just a way to make you come back to buy all your future cards.

The card number encoded is made up of 4 parts:

1.       Parity bits – You don’t need to know about parity bits, just know they are encoded there for added security. They appear at the beginning and end of your encoded data.

2.       The Facility code – When you start a door access program and get prox cards for the first time, you will be given a Facility Code. This is generally a number between 1 and 255. This is used as part of the card encoding to help secure your building.

3.       The card number – This is exactly how it sounds. You start you prox card program at card #1 and go up from there.

Proximity Card Encoding Example:

How to order more prox cards:

You will need to provide 4 pieces of information. All this can be found in the access control panel on-site.

1. Bit Format – 26 (standard), or any number between 24 and 40.

2. Card Type – This is often printed on the card or found in the control panel.

3. Facility code – every building as a different facility code so if you have multiple locations, make sure you get the current facility code.

4. Range of new card numbers – if your last card is #7283 and you want to order 1000 more, your range would be 7284 – 8283. Be very mindful of this sequential numbering and DO NOT overlap card ranges. If two cards are given the same number your system will see them as one card.

Note 1: Any prox format, or card type, can be encoded to match any bit format so if you have a typical prox card and want to start using fobs, you can do that.

Note 2: If you cannot find the above information, you can send us a working card and we can read the data on it and gather all the info we need to help you order your new batch.

Note 3: While HID is the most popular brand, there are more brands that offer a great product at an attractive price. Even if you have HID, you can buy another brand with a 100% money-back guarantee.

Our ID System Specialists are here to help with any questions you may have throughout the process. So just pick up the phone and call, you will get a live person every time! 866.438.4553.

Final Pro Tip – If you are printing on proximity cards, you will get best results with a retransfer printer instead of a direct to card printer. Colors, print clarity and durability of your printer will be better due to the printing technology.