Vaisala WAC155 - Manual (Page 18)

User's Guide ______________________________________________________________________
16 ___________________________________________________________________M210822EN-A
6. Attach the unit on the top of a pole mast with the mounting clamp
as shown in
Figure 17 on page 28 .
7. Mount the sensors onto the cross arm. Refer to Figure 18 on page
29 and the sensors' manuals.
8. Align the cross arm as instructed in section Alignment on page 29
before erecting the mast.
Jumper Settings
RS-485 serial bus termination can be selected with the on-board jumper.
Termination is on when pins 1 and 2 are shorted, and termination is off
when pins 2 and 3 are shorted or when the jumper plug is fully
disconnected. Termination is implemented by a 120 resistor on the
component board.
In a simple point-to-point configuration where only one WAC155
transmitter is used the jumper is always in ON position. In a multidrop
configuration where several WAC155 transmitters share the single
RS-485 communication line, the termination jumper is in ON position
only at the physically farthest transmitter (i.e. at the end of the
communication line), and in OFF position at the other transmitters.
0701-017 Figure 4 RS-485 Termination