Output Wiring – RS485 Interface

The RS485 interface can be wired as two-wire or four-wire wiring and twisted cables must be used. With both variants the load resistance (RT=120 Ω) is the characteristic impedance of the cable.

Two-Wire Wiring

First device

 

 

Last device

 

Second device

Second-to-last device

 

Four-Wire Wiring

First device
(Master)

 

 

Last device
(Slave)

 

Second device
(Slave)

Second-to-last device
(Slave)

 

Connection on the Ignition Controller

 

Wiring of the RS485 interface

Follow these instructions for the RS485 interface wiring:

  • Max. 32 devices can be connected to a bus.
  • The maximum wire length is 100 m (328') depending on the transfer rate.
  • Each bus end must be fitted with a terminating resistor with 120 Ω (as indicated in the drawing).