OMC-131 True wind display
Users’ manual
V1.14
Page 19
TDC-April-2017
Output jumper settings
There are no jumper settings available. The output on port 3 is RS422.
3.3.7 Message format
Currentloop output OMC-160 message format
The currentloop output is normally used to transport the collected data from the currentloop input.
Using the system in this way it is not necessary anymore to output the data as analogue signals
which upgrade the performance and the accuracy. The data is transmitted with the same speed as
data is received from the wind sensor. 300 baud 8N1.
If the currentloop output signal from the OMC-160 is repeated by the OMC-138 the message looks
as follows,
<LF>D125<sp>V234<sp >cscs<CR>
In the above message the transmitted wind direction is the number shown after the indent "D" 125
degrees. the wind speed in the message is shown after the indent "V" 234 is 23.4 m/s. The wind
speed is transmitted without decimal point and must therefore be divided by 10 to get the correct
wind speed.
The checksum is all information in the string added, the least significant byte is divided into high
and low nibble and both nibbles are incremented by hexadecimal 30. This information is sent out as
a checksum.
OMC-2900 message format
Sometimes the data is transmitted in the OMC-2900 format. This format is used when more
parameters are transmitted.
The wind data transported in the OMC-2900 format looks as following,
<STX><LF>V21.2<SP>CSCS< CR>
<LF>D156<SP>CSCS<CR><EOT>
Every message starts with a start of text character after this the messages are transmitted. All
messages start with a line feed followed with the identifier for the data, then the data and then a
checksum for protection reasons, the message end with a carriage return.
All input channels can be transmitted in this way every second to any receiving station.
RS232/RS422 in/output channel
The OMC-2900 and the OMC-160 format on the RS232/RS422 looks the same as the format used
in the currentloop output.
There are two possibilities to transmit data in the NMEA output, wind speed can be transmitted in
m/s or in knots, both messages are shown below.
SIIMWV.123.R.5.8.N.A*24 Wind speed in knots
SIIMWV.123.R.5.8.M.A*27 Wind speed in meters per seconds
