Observator Instruments OMC-140, Руководство по установке

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OMC-140 Installation Manual Page 46
10.3 UDP-tag calculation
A UDP-tag is derived from the ML-tag and added to the NMEA sentence in case it is transmitted over
UDP. In case a UDP-tag is rerouted to be transmitted over serial NMEA, the UDP-tag is removed from
the tag-sentence!
A UDP-tag is identical to a ML-tag using start/stop characters and checksum calculations:
“\s: WIxxxx*hh\”
The WI stands for weather instrument and is static since our instruments only transmit weather related
data.
xxxx can only contain decimal characters (0-9) which are directly derived from the ML-tag of the given
NMEA sentence.
The first x refers to the device type it was sent from:
1
“A”
Meteolink Smart node
2
“B”
Meteolink Basic node
4
“D”
OMC-140 Display
The remaining xxx is a direct copy of the device serial number (last three digits)
For example:
\s: A123
P5 *hh\ (Smart node 123, NMEA port 5)
A
becomes “1”
123 is copied “123”
P5 is ignored for UDP-tag
This makes the UDP-tag:
“\s: WI1123*hh\”
10.3.1 UDP-tag combination
The UDP-tag is always added to the existing ML-tag using comma separation (see NMEA tag standard),
creating
:
\s: A123P5, s:WI1123*hh\
*it is not possible to transmit a NMEA message over UDP without the ML + UDP-tag information!
10.4 NMEA Message description
$--DDC,a,xx,a,a*hh<CR><LF>
1 2 3 4
1. Display dimming preset
2. Brightness percentage 00 to 99
3. Color palette
4. Sentence Status Flag
$--GGA,hhmmss.ss,llll.ll,a,yyyyy.yy,a,x,xx,x.x,x.x,M,x.x,M,x.x,xxxx*hh<CR><LF>
1 2 3 4 5 6 7 8 9 10
1. UTC of position