Access Control System Considerations
- How many users?
How many people will use the system now, and how many may use it in the future? Number of users is the first criteria for choosing an access control system.
- How many doors?
Again, how many doors will have access control now, and how many may have access control in the future?
- Do you want audit trail capability? Do you want time zones?
Audit trail capability allows the administrator to keep track of users as they enter the secured space. The system ‘remembers' when a user presents their credential to the system. We'll discuss credentials shortly. Usually through a computer interface, the administrator can access and/or print out a list of ‘events' including authorized entry, forced entry, and door propped open events.
Time zones are blocks of time assigned to users. If Bob Smith works from 9am to 5pm and you don't want him to come in any other time, time zones allow you to make Bob's credential work only when Bob is authorized to work.
Audit trail and time zone capabilities usually mean that your access control system will interface with a computer using proprietary software supplied by the access control system manufacturer. It is possible to have these features without software, but that usually means that the administrator must punch in commands on a keypad and download audit trail information directly to a printer. A keypad can be a confusing if not frustrating user interface, and the direct print idea is very time consuming, not to mention a waste of paper.
- What kind of credential do you want to use?
The credential is the thing that the user presents to the access control system. The access control system permits or denies entry to the credential when presented. These are the most common types of credentials that are used today:
- Pin code - a series of numbers. The user sequentially presses numbered keys on a keypad. Advantage: numbers are free. Disadvantage: numbers can be shared over the telephone.
If the object is to simply do away with the need to have a key, then a keypad is ideal. All the users can use the same number. Just remember to change the code a few times a year so that the numbers don't get worn off.
- Mag stripe card - like an ATM or credit card, a plastic card with a black magnetic strip across the back. Advantage: common and widely used as well as inexpensive. Disadvantage: they wear out.
- Prox card - proximity card, a PVC card with a computer chip embedded inside. Currently this is the most popular kind of credential. Advantages: it is possible to get a proximity reader that will read the card through the users pants and wallet or inside a handbag. Also since prox cards do not actually need to touch the reader in most cases, they last a very long time. Disadvantage: more expensive than pin codes or mag stripe cards. A slightly more expensive alternative to the prox card is the prox tag or prox key. The prox key is a small, teardrop-shaped credential that can be put on the user's key ring.
- Biometrics - actual body parts. Biometric readers use a live fingerprint, handprint, or the retina of the eye as the credential. Advantages: extremely secure and no credentials to buy. Disadvantage: today in July, 2008, this is still relatively new technology to the field of commercial access control, so the number of choices is fairly small and price tags can be sometimes fairly hefty.
It must also be decided whether the access control system will be hardwired, battery powered, or wireless. The range of choices within these categories is expanding so rapidly at this writing that I will leave this discussion between you and your access control professional. Personally I am most intrigued by systems using PoE (Power over Ethernet) which ties the access control system directly into the LAN for both power and control. Ask your access control professional about this and other possibilities.
The sister topic to access control is electric locking devices, but that is a topic for another time.