CPU CONTROLLER FOR SYSTEM 9770. The CM9760-REL relay interface unit is an optional accessory for System 9700 Series matrix switchers. The unit provides dry contact switching for direct or automatic control of peripheral equipment. The unit connects to any RS-422 COM port on the rear of the CM9700-CC1. The basic function of the relay unit is to allow the user to control various peripheral equipment via relay contacts. Each relay unit processes and executes commands only with addresses that match that of the RELs (frame address). When a relay unit receives a command with an inappropriate address, it passes it on to the next unit (if applicable) via its output port. The front of the relay interface unit has three 10-position DIP switches that configure the communication parameters for the unit as well as setting the parameters for relay contact output operation. The front also has a red data LED that flashes when the first valid command is received. The relay unit mounts in a standard 19-inch (48.26 cm) rack and occupies only 1 RU (1.75 inches or 4.45 cm) of rack space. For remote peration, the wiring from the relay unit to the system controller should not exceed 4,000 feet (1,219m). Daisy-chaining is required when more than 64 relays are needed.Each unit must be configured to have a unique frame address.Daisy-chain configurations can be used whether relay units are situated locally, remotely, or as a combination of the two.