Handling NMEA0183 XDR sentences in Hydromagic
In NMEA0183, the XDR sentence is defined as "Transducer Measurement". The string is mostly used by AirMar to report dual frequency depths, since there is no other NMEA0183 message that supports dual frequency depths. Other applications include reporting of pitch, roll and water temperature and weather sensors.
The string can consist out of one or multiple quadruplets that contain:
- Transducer Type
- Measurement Data (Value)
- Units of measurement
- Name of transducer
Examples of NMEA0183 XDR sentences
Dual frequency depth
$SDXDR,D,2.85,M,XDHI,D,2.92,M,XDLO,C,23.16,C,WTHI*77
$SDXDR,D,2.83,M,XDHI,D,2.92,M,XDLO,C,23.16,C,WTHI*71
Water Temperature
$SDXDR,C,23.13,C,WTHI*76
$SDXDR,C,23.15,C,WTHI*70
Weather Sensor
$IIXDR,P,1.01408,B,Barometer*2B
$IIXDR,C,19.8,C,AirTemp*26
Vessel Motion
$IIXDR,A,4,D,ROLL,A,-2,D,PTCH,A*1A
Examples of NMEA0183 XDR Transducer Types
| Type | Meaning |
|---|---|
| A | Angular displacement |
| C | Temperature |
| D | Depth |
| F | Frequency |
| H | Humidity |
| N | Force |
| P | Pressure |
| R | Flow |
Examples of NMEA0183 XDR units of measurement
| Unit | Meaning |
|---|---|
| B | Bar |
| C | Celsius |
| D | Degrees |
| M | Meter |
| N | Newton |
| P | Percent |
Loading the XDR plugin
The Hydromagic XDR plugin will decode XDR sentences that contain either depth or motion sensor information. Later versions may allow you to record water temperatures along your route as well. In order to decode XDR sentences, the Hydromagic XDR plugin needs to be loaded.
To do so, start the software and select “Preferences…” from the “Options” menu in the menu bar.
From the dialog that appears, select the “Devices” tab and click the “Add…” button to select the plugin from the list that appears next:
Configuring the XDR plugin
Configuration of the plugin is rather simple. First of all, select the source the data comes from.
This can be a serial port, or a network connection over, for instance Ethernet.
Please note that the XDR NMEA0183 data (from sounder) and the regular NMEA0183 data are on different ports.
If this is not possible, there is software around to split one physical serial port into two virtual serial ports on your system.
After configuring the connection, the only thing left to do is to enter the transducer names you want to decode data from.
The most commonly used transducer names are:
- XDLO - Low frequency transducer depth;
- XDHI - High frequency transducer depth;
- PTCH - Vessel motion - pitch;
- ROLL - Vessel motion - roll;
Troubleshooting
When no data is coming in, or you do not know what transducer names are used by your device, you can use the 'Communications Monitor' on this plugin to check the incoming data. In cases where there is no data coming in, check the port number, baudrate and dataformat.
To start the 'Communications Monitor' for this plugin, select 'Preferences…' from the 'Options' main menu. In the window that appears, select the 'Devices' tab. Next, locate the 'NMEA0183 XDR Plugin for Hydromagic' item in the list, and right click to get the context menu. In the menu that appears, select 'Monitor Device...'.
