Appendix A ______________________________________________________________ Networking
VAISALA______________________________________________________________________ 189
RS-485 Serial Interface
Wiring
1. Make the RS-485 wiring of the transmitter as described in Chapter
5 Wiring and Power Management, on 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.
Communication Protocol
Set the communication protocol to ASCII polled (with or without CRC)
or NMEA query. When using NMEA query, the wind message should
be set to XDR (aWU,N=T).
ASCII, Polled
Assign different 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
WXT530 #2 communication settings:
1XU,A=1,M=P,C=3,I=0,B=19200,D=8,P=N,S=1,L=25
WXT530 #3 communication settings:
2XU,A=2,M=P,C=3,I=0,B=19200,D=8,P=N,S=1,L=25
NOTE
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 in order to prevent the units responding to the commands not
assigned to them.
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