Table 6 4-wire (switch 3: on) – Vaisala PTB330 User Manual
Page 47
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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
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