Vaisala WMT52 - Manual (Page 124)

User’s Guide ______________________________________________________________________
122 __________________________________________________________________M210925EN-B
Communication Protocol
Set the communication protocol SDI-12 v 1.3 (aXU,C=1,M=S) or SDI-
12 v1.3 continuous (aXU,C=1,M=R).
WMT52s on the bus shall be assigned with different addresses (for
example: aXU,A=0,1,2, ... ). Thereafter WMT52s on the bus do not
respond to the commands not assigned to them nor to the data messages
sent by the other WMT52s.
Example (A bus with three WMT52s):
WMT52 #1 communication settings:
0XXU,A=0,M=S,C=1,B=1200,D=7,P=E,S=1, L=25
WMT52 #2 communication settings:
1XXU,A=1,M=S,C=1,B=1200,D=7,P=E,S=1, L=25
WMT52 #3 communication settings:
2XXU,A=2,M=S,C=1,B=1200,D=7,P=E,S=1, L=25
If simultaneous measurements of the different units are needed, Start
concurrent measurement commands aC and aCC should be use for all
devices. If the measurements are to be performed consecutively for only
one unit at time, in addition to these also Start measurement commands
aM and aMC can be used. Start continuous measurement commands
aR1, aR5, aR, aRC1, aRC5 and aRC available only in SDI-12
continuous protocol (aXU,M=R) can be used eiher for simultaneous
measurements of the units or consecutive measurements for one unit at
time. See also
SDI-12 Protocol on page 71 .
RS-485 Serial Interface
Wiring
1. Perform the RS-485 wiring of WMT52 as described in Chapter 5,
Wiring and Power Management, on page 39 .
2. In the data logger end, combine the "Data +" wires of each WMT52
to the logger "Data +" wire. Connect the "Data-" wires of each
WMT52 to the logger "Data -" wire.