Power, Control & Data: The Life Blood Of Wired Electronic Access Control Systems

Wired electronic access control systems are comprised of power supplies, input devices such as keypads and card readers, switches and controls, and electrically actuated locking devices and loads.  Similarly, wired data systems such as video surveillance and networked access use wire and are also subject to the Laws of Physics and Voltage Current & Resistance but transmit and receive logic, image and data as well. 

When working with electrical and electronic systems, it is important to be able to perform measurements to get an idea of what it is you are dealing with in terms of voltage, power and signal levels. As the technologies become more sophisticated, so too does the test equipment.

The fundamental measurements performed in electrical and electronic testing are Voltage, Resistance and Current. Wired video and network systems rely on cable infrastructure, which are subject to the affects of Voltage, Resistance and Current over cabling on how they perform. However with video and data, the information is transmitted by means of protocols which use units of measure which require different instrumentation to measure

Commissioning:  The tests performed after the cabling and hardware has been installed, but prior to connecting (terminating) the cabling to the hardware and applying power.

If your system uses discrete power supplies, you may power those up to initially confirm the presence of line voltage and identify the line voltage circuit. Frequently, you can stipulate that the client provide a dedicated breaker and drop (circuit) for your equipment. This ensures there will be adequate power available, and lessens the possibility of accidental overloads or shutdowns of your system by other trades or building occupants. You usually learn of such conflicts of interest once the system has been deployed and the call comes in that your stuff stopped working. To prevent problems caused by other trades or employees overloading circuits, some installers mark circuit breakers and receptacles. That is why hard wired systems (as opposed to receptacles) and restricted access to electrical rooms is standard operating procedure. 

Evaluation: Initial measurements performed after wiring has been completed and power has been applied. If your stuff works, that’s great, but many experienced technicians will put a meter on the system at several points and make a record of initial voltage levels. This way they can verify voltages are within acceptable limits for the various components.

Voltages that are too high may indicate faulty equipment or improperly marked supply circuits. An overvoltage condition can damage or severely shorten the life of your hardware.  

Voltages that are too low may indicate a faulty or improperly rated power supply, low line voltage, excessive voltage drop in the cable between system components, or issues with a load. Examples of this would be a faulty electric lock or wiring to it, or a locking device that is being operated at the wrong voltage.

Power transfers and other wiring within the vicinity of the door should always be checked. Many locking devices require they be wired differently for different voltages, a detail which may be overlooked by trainees, door mechanics or techs in too big a hurry to finish. 

Troubleshooting

Troubleshooting is normally performed on a system that ostensibly was working, but not necessarily installed by you or your company. The system has been in service, and lots of things might have happened since the system was commissioned.

Although having a testing device such as meter for power and switching, or a cable checker for network cabling is very important, being observant and properly evaluating the situation is where you are best to start.

Here’s a scenario: you get the call that the door will no longer unlock on card reader system.

You get to the site and immediately start opening equipment, removing card readers off the wall and dismantling the electric locks to measure and test. Usually the keys to things are not available because the other tech wanted to protect HIS job from interlopers (wired-as drawings are also pretty rare).

Maybe the card reader has been attached to the wall in such a way so that you have to wreck the wall or paint to remove it. Or perhaps the electric lock is on a heavily trafficked door and your working in the doorway immediately causes inconvenience and possibly creates a hazardous condition.

Instead, your first step should be to calmly survey the site, and ask the folks what they observed. They might say things like:

• It never really worked that well, I always had to present my credential numerous times to get in.
• It never opens between the hours if 4 PM and 7AM or on weekends.
• It as fine until we heard a sizzling sound near the door and Mary says she thought she smelled something burning but the smell went away.
• The card reader works fine but I can’t buzz people in anymore

These common sense observations can help you focus and resolve the issues even if you are in a foreign country working on equipment you’ve seen before.

Use The Right Tools

For experienced analog technicians, the advent of the use of UTP cabling and IP protocol has been a challenge. The topology used, Category cable and RJ connectors are specialized and quite different from other low voltage cable and connectors. The voltages and signals used are also different, requiring technicians planning to work with IP to at minimum acquire tools and testers suitable for the tasks.

One vendor to consider is Platinum Tools. Platinum Tools has provided the wire and cable installation tools, connectors and testers, including cutters, strippers, crimpers, testers, cable management, EZ RJ45® CAT5&6 & coax connectors and accessories since 1997.

Net Prowler™ combines network testing (physical layer and link), cable verification & troubleshooting and PoE voltage testing in a handheld tester with a full-color display; all with the capability of saving and printing tests results from a personal computer.

Network Testing

• Tests and reports advertised and current link speed and link speed

• Test TCP/UDP throughput

• Ping both IPV4 and IPV6 addresses

• Tests the presence of VLANs

• CDP/LLDP/NDP and VLAN identification provides network configuration information

• Ping specific URL to verify WAN connectivity

• Blinks link light to identify location on a hub/switch/router port

• Display network devices & associated IP Addresses

For full cable testing on any category network, coax  or telephone cable, Net Prowler will display wire map, numbered ID remotes, and any faults, including shorts, opens, miswires, split pairs, and reverses. It measures cable length (using TDR technology) and generates tone levels for signal tracing and cable identification on all pairs, a selected pair, or a selected pin.

The Net Prowler also enables quick identification of a network drops link capability and current link status. It the presence of PoE on the network drop and what class of PoE per IEEE 802.3 af/at with load test for voltage drop. These network tests can also be saved for record keeping and printing. 

For more information, visit www.platinumtools.com,