ravtrack.com » Message Formats

Identifying Digital Input States in a $PRAVE message

JS — Fri, 05 Feb 2010 05:51:16 +0000

The $PRAVE message has the status of each input as represented by a single digit hexadecimal number in field 12. For example, the the $PRAVE message below, the last 3 represents the digital inputs from transponder 0001.

$PRAVE,0001,0001,3308.9051,-11713.1164,195348,1,10,168,31,13.3,3,-83,0,0,,*66

In this example field 12 has value 3. The field 12 value is the hexadecimal binary representation of the bits. Refer to the following table:

*IN 2* *(TXD)*	*IN 1* *(RTS)*	*IN 0* *(DTR)*	*Hexadecimal Representation*
0	0	0	0
0	0	1	1
0	1	0	2
0	1	1	3
1	0	0	4
1	0	1	5
1	1	0	6
1	1	1	7

The stock RV-M7 GX has up to 3 digital inputs, using the input pins of the RS-232 serial port. An open circuit or ground is a 0, and if they are connected to a positive voltage greater than 3V, they are a digital 1. If all 3 pins are allowed to float (nothing connected – same as ground) the value should be 0. If positive voltage is applied to a pin the pin value will be 1. The field 12 value will be 1 or 2 or 4, depending on which pin had the voltage applied.

RS-232 Pin	Function
4 – DTR	Input 0
7 – RTS	Input 1
3 – TXD	Input 2
5 – Ground	GND	Connect to vehicle chassis or other ground point.

Note that the weatherproofed (-WX) model has less RS-232 pins and only 2 digital inputs. Inputs 1 and 2 are valid, but input 0 is indeterminate (state can float).

In the RavTrack PC software it is easy to not monitor this missing pin, so any change of state or change of value of this pin would not matter to the software. Simply configure this input as unused.

RS-232 Pin	Function
4 – RTS	Input 1
3 – TXD	Input 2
5 – Ground	GND	Connect to vehicle chassis or other ground point.

On the M7 series of transponders, if an input is left floating/unconnected, the transponder will read it as a digital 0 (low), and report it this way.

Vehicle Tracking Message Formats

JS — Fri, 26 Jun 2009 15:50:43 +0000

When a Raveon GPS Transponder received an over-the-air position message from a tracked car, boat, truck, or person, it sends a message out of its serial port. The message it outputs contains the ID of the vehicle that it received the position report from, along with the vehicle’s latitude and longitude.

A typical message would look like this:

$PRAVE,0003,0001,3308.8880,-11713.1500,155010,2,9,179,29,11.6,0,-86,19,-40,,*5B

The above message is in Raveon’s proprietary PRAVE message format. It was from vehicle 0003 whose position is at 33 8.888 north, 117 13.1500 west. Details of the PRAVE message are in the M7 transponder user manual, and on this Tech Blog at http://ravtrack.com/GPStracking/2009/the-prave-message-format/

Raveon’s M7 series of GPS transponders have various built-in drivers enablinging them to output vehicle positions in a variety of different formats. Some formats are in the industry standard NMEA 0183 and other message types are in proprietary formats. The type of message that the M7 transponder sends out it serial port may be configured by the user, using the GPS x command.

Below is a list of message formats that the M7 Transponder supports.

GPS Mode	Common Usage	Default Serial Port Baudrate	Output Message	Description
GPS 1	Transponder Simple tracking, AVL, security.	4800	GSV, GLL	These messages are from the internal GPS only. GPS 1 turns off the radio receiver, so an M7 transponder does receive over-the-air messages.
GPS 2	PC / Base Station Proprietary interface for PC applications that monitor M7 Transponders.	38400	PRAVE	Connect the M7 GX to a PC computer running RavTrack PC (or a custom application), The Raveon proprietary PRAVE message is in NMEA format, and provides location and status information for every transponder it receives.
GPS 3	Marine Radar Displaying the location of M7 transponders on a ship RADAR screen.	38400	TLL	Used when the M7 GX is connected to a marine RADAR display or plotter with a serial port, and waypoints will appear on the GPS screen at the location of all M7 GX transponders within radio range. The display must support the NMEA 0183 TLL message.
GPS 4	GPS Display Lowrance and Garmin GPS displays. Mobile displays.	4800	WPL	Connect the M7 GX to a mobile or hand-held GPS with a serial port, and waypoints will appear on the GPS screen at the location of all M7 GX transponders within radio range.
GPS 5	-LX No GPS module Lowrance and Garmin GPS displays. Radar displays. Mobile displays.	38400	PRAVE	Connect the M7 GX to a PC running RavvTrack PC, or change the message to WPL and use with a GPS display. No internal GPS, so no positions/status transmissions.

The $PRAVE Message Format

JS — Thu, 05 Mar 2009 09:44:40 +0000

Overview

Over-the-air position/status messages that the M7 GX transceiver and the Personal Locator may receive are sent out the serial port using Raveon’s proprietary message format called the $PRAVE message. The $PRAVE message is used to pass the tracked vehcile’s ID, location, speed, and status. The $PRAVE message format is the default message format when the unit is configured for GPS mode 2.

Structured like a standard NMEA GPS message, the $PRAVE message contains a rich set of location and status information. The $PRAVE message is sent out the serial port of the radio, each time the radio receives a position message over-the-air.

Please note, the $PRAVE message is not transmitted over-the-air. Raveon transmits over-the-air a highly compressed form of the data held in the $PRAVE message. When an M7 GX receives this over-the-air position/status report, the received information is decompressed and the data is sent out the serial port, in one of a number different formats. One of these formats is this $PRAVE message. Other options are the NMEA $GPWPL message and the $GPTLL message. These are covered in the user manual for the M7 GX radio transponder.

$PRAVE Message Format

The $PRAVE message is sent out the RV-M7 GX when it is configured for GPS 2 mode of operation. This mode is typically used with the RavTrack PC program, or other computer programs that can process position and status information. GPS mode 2 instructs that the output be sent at 38.4K bytes/second out the serial port.

Along with ID and position information, the $PRAVE contains a host of other status information. The length of this message may exceed he standard NMEA limit of 79 characters. Any product or software that uses this message must take this into account.

Following is a list of the fields sent in this message

Field	Usage	Comments
1	$PRAVE	Raveon Proprietary Header
2	From ID	The ID of the transponder that transmitted its position over the air. It is a decimal number, 0 – 9999.
3	To ID	The ID that this position report was sent to. It is a decimal number, 0 – 9999.
4	Latitude	dddmm.mmmm format. It is signed. + is north, – is south. No sign means north. Note: typically there are 4 decimal places, but as few as 0 decimal places are possible. Null field if no GPS lock.
5	Longitude	dddmm.mmmm format. It is signed. + is east, – is west. No sign means east. Note: typically there are 4 decimal places, but as few as 0 decimal places are possible. Null field if no GPS lock.
6	UTC time	The UTC time at the time the transmission was made. Hhmmss format. Null field if no GPS lock.
7	GPS Status	0=not valid position. 1=GPS locked and valid position.
8	Num Satellites	The number of satellites in view
9	Altitude	The altitude in meters. Null field if no GPS lock.
10	Temperature	The internal temperature of the RV-M7 in degrees C. Typically this is 5-20 degrees above ambient.
11	Voltage	Input voltage to the device that sent this position.
12	IO status	A decimal number representing the binary inputs.
13	RSSI	The signal-strength of this message as measured by the receiver, in dBm. Note, if the message went through a repeater, it is the signal lever of the repeated message.
14	Speed	The speed of the device in km/hour, 0-255
15	Heading	The heading of the device 0-360 degrees.
16	Alerts	Alert codes for alerts currently indicated in the device. NULL means no alerts. “P” means a proximity alert. “A”means alert. “C” means critical alert, “M” means man-down.
17	Spare	A spare field. May be used for UTC date in the future. Typically NULL.
18	*	The “*” NMEA end-of-message identifier.
19	Checksum	The NMEA 0183 checksum.

Example Sentence:

$PRAVE,0001,0001,3308.9051,-11713.1164,195348,1,10,168,31,13.3,3,-83,0,0,,*66

This example shows a unit at 33° 8.9051 north latitude and 117° 13.1164 east longitude. It is not moving (0 speed). Its signal strength was -83dBm. Its altitude is 168 meters.

For your curiosity or testing purposes, below is a capture of vehicle 0003 driving around the Raveon office in Vista, California.

$PRAVE,0003,0001,3308.9077,-11713.1259,154656,1,8,200,24,11.6,0,-69,0,0,,*76
$PRAVE,0003,0001,3308.9082,-11713.1262,154716,2,8,199,24,11.6,0,-64,0,0,,*7C
$PRAVE,0003,0001,3308.9084,-11713.1267,154736,2,8,198,24,11.6,0,-64,0,0,,*7C
$PRAVE,0003,0001,3308.9092,-11713.1288,154756,2,9,198,24,11.6,0,-61,4,-298,,*52
$PRAVE,0003,0001,3308.9225,-11713.1239,154816,2,8,195,25,11.6,0,-62,8,-18,,*65
$PRAVE,0003,0001,3308.9418,-11713.1146,154836,2,9,190,26,11.6,0,-85,3,-14,,*6D
$PRAVE,0003,0001,3308.9532,-11713.1314,154842,2,9,186,26,11.6,0,-96,38,-294,,*65
$PRAVE,0003,0001,3308.9654,-11713.1665,154846,2,9,182,26,11.6,0,-102,61,-292,,*53
$PRAVE,0003,0001,3308.8880,-11713.1500,155010,2,9,179,29,11.6,0,-86,19,-40,,*5B
$PRAVE,0003,0001,3308.9120,-11713.1327,155030,2,9,183,30,11.6,0,-72,1,-206,,*57
$PRAVE,0003,0001,3308.9116,-11713.1304,155050,2,9,191,31,11.6,0,-71,0,0,,*7C