Vaisala PTB330 - Manual (Page 47)

Chapter 3 _______________________________________________________________ Installation
VAISALA _______________________________________________________________________ 45
Table 6 4-Wire (Switch 3: On)
RS-485 master Data PTB330
TxD+ -> RxD1+
TxD- -> RxD0-
RxD+ < - TxD1+
RxD- < - TxD0-
Common N/A Common
Termination
Termination Junction box
Junction box
Junction box
120R
D0-
D1+
Common
Switch
Term off
Term off
2/4 wire off
RS422 off
Stub
Stub
Stub
RS485-1
RS485-1
RS485 bus master
Twisted pair
Address NN
Address MM
Common
D0-
D1+
Switch
Term off
Term off
2/4 wire off
RS422 off
Common
D0-
D1+
5
4
3
2
1
5
4
3
2
1
120R
1102-027
Figure 27 2-Wire RS-485 Bus
Table 7 2-Wire (Switch 3: Off)
RS-485 master Data PTB330
A <-> A
B <-> B
Common N/A Common