Siemens SITRANS F MAG 8000 Standard Operating Instructions Manual page 38

Connecting
5.5 Communication modules
RS 485 connection diagram
①
②
③
①
②
A Modbus RS 485 must use a balanced pair (for D+ - D−) and a third wire (for common).
For the balanced pair used in an RS 485 system, a characteristic impedance with a value
between 100 and 120 ohms must be used.
Shield must always be connected to MAG 8000 encapsulation using cable clamp as shown in
figure in section cable installation, see Power supply (Page 34).
Bus termination:
All RS 485-based networks must be terminated correctly to function properly. A termination
must be placed at each end of segment.
The Modbus RTU module can add a 120 ohm termination if a jumper is placed beside terminals
in position "ON".
Termination is set to "ON" from factory.
38
Common
Connect shield to encapsulation
Shield must be connected to protective ground
Common
Termination
Operating Instructions, 11/2018, A5E03071515-AE
SITRANS MAG 8000