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Operating manual ZX09/20/21-Series
7.2.2 Modbus RTU wiring
The connection of one or more Zander controllers to a Modbus RTU Master is made
via the connections 2+ and 2- of the RS-485 interface using a shielded twisted-pair
two-wire cable (see Fig. 24). The shield must be connected to a shielding rail at one
end with low impedance as close as possible to the device.
The topology of an RS-485 bus connection with several Modbus RTU participants is
shown in Fig. 25. A terminating resistor of 120 Ohm must be used at the last
participant in the bus.
1+
1-
2+
2-
Ck+
Ck-
D+
D-
RS-485
SSI
Shield rail
(PE)
Fig. 24: RS-485 wiring (e.g. on ZX09A)
