Compac CNG Service Manual page 109

Electrical Drawings and Component Details
RS485 Wiring
Connecting RS485 equipped dispensers to controller.
Compac Industries Ltd.
Wiring typically uses 3 cores of a 4 core SWA two twisted pair cable
connected to the terminals on J12 named TXDP, DTRB and GNC inside the
C4000 box. If connecting multiple dispensers, always wire them in parallel.
At the site controller, the terminals may be named: RS485A = TXDP and
RS485B = DTRB. GND = Ground or Earth.
The C4000 box contains mains voltage power. Always isolate
before removing the lid.
Page 109
C4000 Microprocessor Board
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