Bus Termination - ABB FMBA-01 User Manual

18

Bus termination

Bus termination is required to prevent signal reflections from the
bus cable ends. The FMBA-01 Modbus Adapter module is
equipped with internal bus termination, which is configurable with
jumper J1 pins. Termination should be activated on devices
located at bus ends and deactivated on other devices. See the
figure below.
J1
Termination
activated
RS-485 device
Term.
ON
Electrical installation
RS-485 bus termination
J1
Termination
deactivated
RS-485 device
Term.
OFF
J1
Termination
deactivated
RS-485 device
Term.
OFF
J1
Termination
activated
RS-485 device
Term.
ON