Vaisala MMT330 - Manual (Page 62)

User's Guide _______________________________________________________________________
60 ___________________________________________________________________ M210733EN-G
1102-027
Figure 35 2-Wire RS-485 Bus
Table 8 2-Wire (Switch 3: Off)
RS-485 master Data MMT330
D1+
↔
D1+
D0-
↔
D0-
8. When operating in communication mode RS-422, set both switches
3 and 4 to ON position (4-wire wiring is required for RS-422
mode).
9. Connect the power and close the cover.
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 Common line
Address NN
Address MM
Common
D0-
D1+
Switch
Term off
Term off
2/4 wire off
RS422 off
Common
D0-
D1+
120R
Twisted pair Common line