Problem
A customer asked Alpha Omega to develop a monitoring and control unit for security and access control applications. The device must have 32 Class B Alarm inputs, some high power switched outputs, a serial communications network, and must operate from a battery if AC power fails.
Solution
AO designed the unit around the then state of the art 68070 processor, with sockets for a large amount of static RAM and EPROM memory. A 12-bit Analog to Digital converter monitored multiplexed general-purpose analog inputs that could be configured for a variety of alarm monitoring protocols, including Class B. Eight high power relays (8 Amp at 250 VAC, 5 Amp at 30 VDC, ¼ horsepower) provided output control. Individual LEDs provided a display of the 32 input states and eight output states. Provision was made for addition of a liquid crystal display panel. The unit contained a battery charging circuit to keep the external standby battery fully charged.
Four synchronous or asynchronous half or full duplex RS-485 serial I/O ports allowed the unit to be connected into multiple networks to provide a distributed control system for large buildings or campuses. An additional bidirectional serial port could be configured with a front panel rotary switch for RS-485, RS-232 or current loop operation. Rotary switches also allowed setting unit address, serial baud rate and selecting several different test modes that were used during installation. A separate group of LEDs provided continuous display of operating state and test conditions.
The unit was housed in a rack mountable heavy duty steel case. Connections to the unit were made with plug in connectors to make removal and replacement a fast and simple operation without having to disconnect and reconnect dozens of wires.
Results
The Monitor Point Controller served in a number of distributed security and access control installations.