USER'S GUIDE____________________________________________________________________
54 __________________________________________________________________ M210762EN-D
Table 6
Connecting Twisted Pair Wires to Screw
Terminals
Screw terminal
Data line
(2-wire RS-485)
Data line
(4-wire RS-485/422)
1 (not
connected)
RxB
2 (not
connected)
RxA
3
Data pair shield
Data pair shield
4 B
TxB
5 A
TxA
6.
If you use RS-485 (or RS-422) to connect just one DMT346 to a
master computer, enable the internal termination of DMT346 by
switching switches 1 and 2 ON. Make sure that the master's end of
the line is also terminated (by using master's internal termination or
with a separate terminator).
If you are connecting many transmitters to the same RS-485 bus,
make sure that switches 1 and 2 are OFF and terminate the bus with
separate terminators at both ends. This allows removing any
transmitter without blocking the bus operation.
NOTE
If you use the internal termination of the transmitter at the end of the
RS-485 bus (instead of using separate terminators) removing that
transmitter will block the bus operation.
7.
Use the bus type (4-wire/2-wire) to select the selection switch 3.
In 4-wire mode RS-485 master sends data to the DMT346 through
terminals RxA and RxB and receives data from DMT346 through
terminals TxA and TxB.