Vaisala WAC155 - Manual (Page 34)

User's Guide ______________________________________________________________________
32 ___________________________________________________________________M210822EN-A
More than one transmitter can be connected to a single RS-485 bus.
In the case of single transmitter, the auto-transmit mode can be used (the
device transmits data messages with configured interval). If there are
several transmitters in the same bus, auto-transmission may not be
enabled, and data can be only polled by query.
Each device in the same bus has a unique configurable ID, containing
1..5 characters. Alphabetical characters a-z and A-Z (case-sensitive) are
accepted, as well as numbers 0-9.
NMEA Message Format
The NMEA specification defines wind speed and angle message MWV
as follows:
$WIMWV,<a.a>,<R>,<s.s>,<U>,<S>*<CS><cr><lf>
The comma "," is used as a separator between the fields. Here are some
examples of MWV messages output by the WAC155:
Table 4 WAC155 Default Serial Communication Settings
Property Description / Value
Baud rate 9600
Data bits 8
Parity none
Stop bits 1
where
$WIMWV = Fixed text at the start of the message
<a.a> = Wind angle, 0..359 degrees
<R> = Reference: R=relative, T=theoretical
<s.s> = Wind speed
<U> = Units: K=km/h, M = m/s, N=knots
<S> = Status: A=valid, V=invalid
* = Asterisk, indicating that the next field is the checksum
<CS> = Two character checksum for the message