Figure 17 Mns Digital Gateway Rs485 Connection Via Serial 2; Figure 18 Example For Rs485 Bus Termination And Biasing - ABB M101 Manual

CO M M U N I CATI O N I N TE R FA CE CO N NE CT IO N
5.4.1.3. RS485
Allows multi drop topology with a maximum of 31 devices on the link. The maximum distance
according to the standard is 1000 meters (depending on communication speed

Figure 17 MNS Digital Gateway RS485 connection via Serial 2

5.4.1.4. Termination
The RS485 bus must be terminated at both end.
The MNS Digital Gateway does not provide an in-built MODBUS RTU termination for RS485
communication; therefore correct measures must be taken to connect termination to both
ends of the segment.

Figure 18 Example for RS485 bus termination and biasing:

1TG C 9 0 8 0 0 4 M 0 2 0 1
F I E L D B U S
2 3