How to Choose RFID Fobs for Access Control and Time Attendance

Fobs for a whole building or company are ordered once every few years, which makes it all the easier to pick the wrong type. A reader will not accept a chip it does not support, and a box of fobs ends up in a drawer. Let us go through what to check in advance. At the end you will find a checklist that helps you order correctly the first time.

What does an RFID access control system consist of?

Every chip-based system has three parts:

• A reader at the door, turnstile or attendance terminal, which reads the chip.
• A controller with software, where the administrator keeps the list of authorised users and sets who may enter where and when.
• Credentials in the form of key fobs, cards or wristbands carried by users.

When you buy more fobs for a working system, you do not change the reader or the software. The new fobs only have to match what the reader supports, and the administrator then adds them to the system. We explain how the technology works inside in a separate article, What is RFID and how does it work.

How do you find out which chips your reader supports?

The reader type is the key piece of information for your order. You can get it in three ways:

1. The reader's documentation or label. The manufacturer lists the frequency and supported chip types, such as EM4100 or MIFARE.
2. The system administrator or supplier. In an apartment building, ask the building manager or the company that installed the entrance. In a company, ask your IT or facility manager.
3. A quick phone test. Hold your current fob to an Android phone with NFC switched on. If the phone reacts, the chip works at 13.56 MHz. If it does not, it is most likely a 125 kHz chip.

Note that a matching frequency is not enough. The HF band includes many chip types, and a reader configured for MIFARE DESFire may reject an older Classic chip. The safest approach is to know the exact type of the chip you use today.

Also watch out for proprietary formats. Many systems, especially in the UK and the US, use HID Prox or HID iCLASS credentials. They also work at 125 kHz or 13.56 MHz, but with their own formats, so EM4102 or MIFARE fobs will not work with them. If your reader carries the HID logo, check its configuration before ordering.

What level of security do you need?

Apart from frequency, chips differ mainly in how well they protect the entrance. For clarity, we divide them into three levels:

A chip that carries only an ID number can be imitated, and experts consider the original Classic encryption broken. If you protect a warehouse with valuables or a server room, encrypted DESFire is worth the investment. For the entrance door of most apartment buildings, the medium level is enough.

Key fob, card or wristband?

The same chip comes in different housings, and each has its strengths:

• A key fob stays on the key ring, so people do not forget it. It withstands rough handling and can carry a printed logo or an engraved number.
• A card fits in a wallet and offers a large printable area, for example for an employee's photo and name. Companies therefore often use it as an ID badge as well.
• A wristband suits pools and events where people have no pockets. For pools, the water-resistant Smart key fob is a practical alternative.

Apartment buildings: what to keep in mind

The order for a building is usually handled by the building manager or the homeowners' association. These tips will save you trouble:

• Fobs per flat. Usually two to four depending on the number of residents. Add fobs for the caretaker, cleaning staff and technicians.
• A reserve. Order about 10 to 20% extra. New tenants, lost keys or a broken fob come sooner than you expect.
• A record of numbers. Every chip has its own ID number. Keep a note of who received which one, and have serial numbers engraved on the fobs so you can match them at a glance.
• A lost fob. The administrator blocks the lost chip in the system by its number and issues a new one. There is no need to change locks as with ordinary keys.

Companies: one chip for entry and attendance

In a company it pays off when one chip opens the doors and records attendance at the same time. An encrypted MIFARE DESFire EV3 chip can hold data for several applications in its memory, so it handles entry, attendance and canteen payments.

Companies also appreciate personalisation. A name or employee number on the fob makes record-keeping easier, and colours distinguish departments or visitors. The attendance system itself, meaning the software and terminal, comes from its manufacturer. We supply the fobs for it.

Gyms, swimming pools and clubs

Sports facilities have their own demands. Fobs get wet, fall on tiled floors and are used by hundreds of people every day. We therefore recommend:

• a water-resistant fob, such as the ultrasonically welded Smart model,
• one chip for the turnstile and the locker, so members do not have to carry two things,
• colours by membership type, for example annual and monthly passes.

How many fobs to order and how to mark them

You can order our fobs individually, with no minimum quantity, and delivery usually takes 1 to 3 weeks. If you plan to grow, order a reserve straight away anyway, so that engraved numbers continue in one unbroken series.

You can have these placed on the fob:

• a logo by full-colour printing,
• a serial number or QR code by laser engraving, which does not wear off with frequent use.

We need your artwork in a vector format such as EPS, AI or SVG. Send it by e-mail after you place the order.

Checklist before you order

Before you send the order, go through these points:

• Reader frequency: 125 kHz or 13.56 MHz?
• The exact chip type, with an old fob for comparison.
• No proprietary format such as HID Prox or iCLASS.
• The level of security you need.
• Carrier: key fob or card?
• Number of pieces, including a reserve.
• Your logo as a vector file and a decision on numbering.
• Agreement with the administrator on who enrols the fobs in the system.

Frequently asked questions

Will new fobs work with our old reader?
Yes, if both the frequency and the chip type match. The safest way is to send us the reader model or your current chip and we will check it for you.

Who adds the fobs to the access system?
Your system administrator or installer. Simpler systems only need the chip number. Encrypted chips have to be programmed by whoever holds the keys, so agree on this in advance.

What if a fob is lost?
Report it to the administrator. They block the lost chip and activate a new one in its place, ideally from the reserve you keep at hand.

Can I order just one or two fobs?
Yes. There is no minimum order quantity. Keep in mind that the new fob still has to be enrolled in your system by its administrator.

We will help you choose

To choose well, you only need to know your reader, decide on the level of security and order with a reserve. In our shop you will find RFID key fobs as well as contactless cards. Send your reader model or a photo of your current chip to sales@qscd.eu and we will suggest a suitable solution.