Fieldbus; Modbus Rtu Topology; Figure 15 Mns Digital Gateway Rs232 Connection Via Serial 2 - 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. Fieldbus

5.4.1. Modbus RTU Topology

There are three options for MODBUS RTU interface (Serial 2 Sub-D connector) available for
the MNS Digital Gateway which can be selected by parameter in MNavigate tool: RS 232, RS
422 and RS 485.
Max. cable length varies from 15m (RS232) up to 1200m (RS485/422) depending on transmis-
sion speed and repeater type in use. Cable length can be extended using fiber optic modems
which in addition also galvanically isolate the communication, prevent shield currents and
provides best option for EMC immunity.
The serial port interface of the MNS Digital Gateway is not galvanically isolated. To
achieve this it is recommended to use 3rd party products.
5.4.1.1. RS232
Allows only a simple point to point topology between Master and Slave. The maximum dis-
tance according to the standard is 15 meters.

Figure 15 MNS Digital Gateway RS232 connection via Serial 2

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