Saturday, March 21, 2009

78. IP readers.

Readers are connected to a host PC via Ethernet LAN or WAN. Advantages:Most IP readers are PoE capable. This feature makes it very easy to provide battery backed power to the entire system, including the locks and various types of detectors (if used). IP readers eliminate the need for controller enclosures. There is no wasted capacity when using IP readers (i.e. a 4-door controller would have 25% unused capacity if it was controlling only 3 doors).

IP reader systems scale easily: there is no need to install new main or sub-controllers. Failure of one IP reader does not affect any other readers in the system. Disadvantages:In order to be used in high-security areas IP readers require special input/output modules to eliminate the possibility of intrusion by accessing lock and/or exit button wiring. Not all IP reader manufacturers have such modules available.

Being more sophisticated than basic readers IP readers are also more expensive and sensitive, therefore they should not be installed outdoors in areas with harsh weather conditions or high possibility of vandalism. The variety of IP readers in terms of identification technologies and read range is much lower than that of the basic readers. The advantages and disadvantages of IP controllers apply to the IP readers as well.5. Network-enabled main controllers. The topology is nearly the same as described in the second and third paragraphs.

The same advantages and disadvantages apply, but the on-board network interface offers a couple valuable improvements. Transmission of configuration and users to the main controllers is faster and may be done in parallel. This makes the system more responsive and does not interrupt normal operations. No special hardware is required in order to achieve redundant host PC setup: in case the primary host PC fails, the secondary host PC may start polling network controllers. The disadvantages introduced by terminal servers (listed in the fourth paragraph) are also eliminated.

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