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Proprietary NMEA Sentences
The MiniPlex multiplexers are configured with proprietary NMEA sentences that can be sent to the
multiplexer through the host interface.
The multiplexer can also output proprietary NMEA sentences on a host interface to output status
information or a response to a received proprietary NMEA sentence.
The multiplexer also outputs some standard NMEA sentences. These sentences all start with ‘MX’, which
is the talker ID for a multiplexer as defined by the NMEA standard.
All MiniPlex proprietary sentences have the following format:
$PSMDxx[,a,b,…][*hh]<CR><LF>
$P:
Start of a proprietary command as dictated by the NMEA standard
SMD:
ShipModul manufacturer mnemonic
xx:
Two- or three-character sentence formatter
a,b,…:
Optional fields
hh:
Optional checksum
<CR><LF>: Carriage Return and Line Feed characters that terminate the sentence
Unless specified otherwise, fields are optional (except the Sentence Status field) and may be skipped
when no change is required. For instance, a $PSMDCF,C,,,,1 sentence only enables Channel Numbers.
The preceding fields are skipped (,,,,) and the trailing fields are omitted.
For ease of manual configuration, these sentences do not require a checksum. If the sentence has a
checksum however, it is checked and the sentence is rejected when a checksum failure occurs. Sentences
output by the multiplexer always contain a checksum unless the checksum check is switched off.
Checksums are denoted with *hh in the descriptions below.
Unless specified otherwise, all command sentences return a status report of their settings when sent
without parameters.
Thus a $PSMDCF sentence will return $PSMDCF,R,b,s,p,n,rrrrr,h,v,t,f,r*hh<CR><LF>
Most sentences have a Sentence Status field that indicates whether the sentence is a status report or a
command. The first field of the sentence contains an ‘R’ when the sentence is a status report as a result
of a sentence without any parameters. The first field contains a ‘C’ when the sentence is a command to
the multiplexer.
A sentence with its Status Field set to ‘R’ is ignored by the multiplexer.
Example
When a $PSMDID sentence is sent to the multiplexer, it will respond with $PSMDID,R,aa,bb,cc,dd,ee*hh
To send this sentence as a command to the multiplexer, $PSMDID,C,aa,bb,cc,dd,ee should be sent.
$PSMDCF – Set Configuration
This sentence sets various configuration settings of the multiplexer.
Format: $PSMDCF,a,b,rrrrr,t*hh<CR><LF>
a:
Sentence Status flag:
R = sentence is a status report of current settings
C = sentence is a command to change settings
b:
Baudrate selector for the RS-232 interface (ignored when no RS-232 port present):
0 = 4800 Baud
1 = 9600 Baud
2 = 19200 Baud
3 = 38400 Baud
4 = 57600 Baud
5 = 115200 Baud
rrrrr:
Real-time mode:
0 = off
1 = on
Five digits, one digit per input, 1 to 5 from left to right. Input 5 is the source of internally
generated sentences from NMEA conversions.
