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Service Manual Combics
Switch Function when switch is closed
SW1-1 Load resistor, TX side 120 Ohm
SW1-2 BIAS resistor, TX side (TXD+, Pull-Up) 680 Ohm
SW1-3 BIAS resistor, TX side (TXD-, Pull-Down) 680 Ohm
SW1-4 RS-422 operation= A2 (open: RS-485 operation = A3)
SW2-1 Load resistor, RX side 120 Ohm
SW2-2 BIAS resistor, RX side (RXD+, Pull-Up) 680 Ohm
SW2-3 BIAS resistor, RX side (RXD-, Pull-Down) 680 Ohm
SW2-4 Not used
Digital I/O Option (A5) Assignment
The Digital I/O PCB is connected to the slot of the UNICOM interface
Configuration options are not available.
Connections assignments are listed in the following table:
Interface Description | Unicom PCBs
Open
Closed