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Figure 35, Wire rs-485 bus, Table 7 – Vaisala MMT330 User Manual

Page 60: Wire (switch 3: off)

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User's Guide _______________________________________________________________________

60 ___________________________________________________________________ M210764EN-F

1102-027

Figure 35

2-Wire RS-485 Bus

Table 7

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