System’s that have the Controller built into the computer have inherent problems. Although these systems are cheaper to manufacturer they are usually sold for about the same price as a system with an independent controller. Any system based on a PC has inherent problems such as hanging, servicing and power failure recovery. These systems are usually sold as integrated systems and sell this as a feature, when in reality it will be a nightmare. By integrating the controller into the PC, if you have a problem, your gate service person will not be able to solve any computer problems, and your PC service person will blame the other person. Since your PC must be on 24 hours a day, and in most cases not attended, if power is lost while accessing the hard drive, you may loose the ability to access the drive after power is restored. Most systems will need a human being to restart the computer, usually causing problems with your customers. |
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Failures due to lightning strikes are a very serious problem in many areas. Most manufacturers say they have lightning surge protection, but actually have none or only low voltage surge protection. This low voltage surge protection is usually accomplished by the use of surge diodes. These surge diodes are placed across the circuit to be protected and should also be placed between each line and earth ground. This configuration of surge diodes will protect the circuit against moderate voltage spikes such as spikes on the power line caused by a motor turning on and off, but will not handle the high energy associated with lightning generated spikes. Some competitors have added gas tubes as a second stage of protection in front of the surge diodes. These devices are designed to remove voltages and currents in the thousands of volts/amps. The problem with this approach is that the gas tube will not start to work until the voltage is over 100 volts, far above the voltage that will destroy the electronics it is designed to protect. By designing in an intermediate stage to trigger the gas tubes, while protecting the equipment from being destroyed produces a lightning protection system that actually works. Another problem is that most systems are not grounded properly making what protection they have ineffective. Demco Electronics is the only company that has three-stage lightning surge protection and have placed this protection where it will do the most good. Demco keypads are available with this three-stage lightning surge protection built-in and since the keypads are outside or near the entrance of a building, a good earth ground is usually available. A good earth ground usually can not be obtained for the devices when the devices are located deep inside the building. A poor earth ground at the devices will reduce or destroy any lightning surge protection built-into the device. We have developed a three-stage protector as a stand-alone product in order to protect the controller, multiplexers and other devices located in the buildings from lightning energy entering the system through the cabling. By mounting this protector where the cabling enters the building enables the installer to provide a good earth ground connection, eliminating the lightning energy from entering the devise in the first place. |
The keypads used in these systems have been a chronic problem in the industry because they are usually located outside and not protected from vandalism and the environment. Demco Electronics is the only manufacturer that seals the keypads not only from the front but also from the rear. Sealing the keypads from the front protects the contacts in the keypad switch and sealing the keypads from the rear protects the device number switches, adjustment pots, plugs and the printed circuits from corrosion. |