3.2.3 Wiring RS485 full duplex
5 4 3 2 1
9 8 7 6
COMBIVERT
5 4 3 2 1
9 8 7 6
COMBIVERT
4 5
8 9
4
5 7
7
8
9
Master
TxD-A
TxD-B
RxD-A
RxD-B
R
R
R
R
R=120Ω
1)
1) The ground connection is used to reduce communication disturbances
Figure 5:
Wiring RS485 full duplex
3.2.4 Wiring RS485 half duplex
5 4 3 2 1
9 8 7 6
COMBIVERT
4
5
8
9
5 4 3 2 1
9 8 7 6
COMBIVERT
4
5
8
9
Master
RXD/TxD-A
RXD/TxD-B
R
R
R=120Ω
7
7
1)
1) The ground connection is used to reduce communication disturbances
Figure 6:
Wiring RS485 half duplex
Although the functional earth is connected correctly potential differences between the bus nodes can
occur at long lines which disturb the communication. To avoid the interface from destruction by high
circulating current based on this, potential differences can be reduced by connection of an addition-
ally ground line between the controls (0V terminal). To avoid interference coupling into the signal line,
lay these additionally ground cable outside of the bus line !
18
CONTROL CIRCUIT ANALOG/DIGITAL
