Vaisala WXT530 Series - RS-485 Serial Interface

2XXU,A=2,M=S,C=1,B=1200,D=7,P=E,S=1, L=25
If simultaneous measuremen
ts of the dierent units are needed, Start concurrent
measur
ement commands aC and aCC must be used for all devices. If the measurements are
to be performed consecutively for only one unit at a time, in addition to these also Start
measurement commands aM and aMC can be used. Start continuous measurement
commands aR1, aR2, aR3, aR5, aR, aRC1, aRC2, aRC3, aRC5 and aRC available only in
SDI-12 continuous protocol (aXU,M=R) can be used either for simultaneous measurements
of the units or consecutive measurements for one unit at time.
A.3 RS-485 Serial Interface
A.3.1 RS-485 Wiring
1. Make the RS-485 wiring of the transmitter. See 5
. W
iring and Power Management
(page 53).
2. In the data logger end, combine the "Data +" wires of each transmitter to the logger
"Data +" wire. Connect the "Data-" wires of each transmitter to the logger "Data -" wire.
A.3.2 RS-485 Communication Protocol
Set the communication protocol to ASCII polled (with or without CRC) or NMEA query.
When using NMEA query
, the wind message must be set to XDR (aWU,N=T).
No matter which communication protocol, ASCII polled or NMEA query is chosen, the
error messaging parameter of the supervisor message must be inactivated with aSU,S=N
for each transmitter on the bus to prevent the units responding to the commands not
assigned to them.
A.3.3 ASCII, Polled
Assign dierent addresses to the transmitters on the bus (for example, aXU,A=0,1,2, ...).
Example (a bus with three transmitters):
WXT530 #1 communication settings:
0XU,A=0,M=P,C=3,I=0,B=19200,D=8,P=N,S=1,L=25
WX
T530 #2 communication settings:
WXT530 Series User Guide M211840EN-D
172
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