Vaisala WXT520 Guide de l'utilisateur télécharger pdf (Page 153)

Appendix A ______________________________________________________________ Networking

VAISALA______________________________________________________________________ 151

RS-485 Serial Interface

Wiring

1. Make the RS-485 wiring of WXT520 as described in Chapter 5,

Wiring and Power Management, on page 43.

2. In the data logger end, combine the "Data +" wires of each

WXT520 to the logger "Data +" wire. Connect the "Data-" wires of

each WXT520 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

WXT520s on the bus shall be assigned with different addresses. (for

example: aXU,A=0,1,2, ... ).

Example (a bus with three WXT520s):

WXT520 #1 communication settings:

0XU,A=0,M=P,C=3,I=0,B=19200,D=8,P=N,S=1,L=25

WXT520 #2 communication settings:

1XU,A=1,M=P,C=3,I=0,B=19200,D=8,P=N,S=1,L=25

WXT520 #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 disactivated with aSU,S=N for each WXT520 on the

bus in order to prevent the units responding to the commands not

assigned to them.

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Vaisala WXT520 Guide de l'utilisateur Page 153