Using UDP communication. Through the GPRS network.

Message format in detail

Message General Format

All messages are used as a common format for transmission:

2 1 2 4 N 1 1

packet header Command length pseudo-IP parameter Checking code Packetail

Refers to the data of the frame border, header occupies 2 bytes length (the new agreement as 0x24 0x24, the old agreement as 0x29 0x29), length of packet tail occupies 1 byte (0x0D)

Serial number

A set of instructions and response process identifier, used to match the downlink and uplink command response consistency. Note that the serial number from the center to maintain, HEX format, network byte order, increase. Response time to populate the corresponding terminal command to bring down the serial number to the center. Terminal message issued on the initiative of the position to zero.

Main signaling

Keyword refers to the air signaling protocol

Packet length

Paul refers to the contents of the data length, packet length bytes from the first byte after the start position until the end of packet length, occupies 2 bytes. The default network byte order is big endian mode

Pseudo-IP address

Refers to the method by specifying the unique identifier number into a terminal pseudo IP address of four bytes

Parameter

And the parameters to match the main signaling domains, the length of 0-N

Check

Refers to the packet header from the beginning, after a byte XOR with, until the previous calibration byte occupies 1 byte

More packets are in hexadecimal byte stream, the message does not exceed the total length of 512 bytes!

29 29 30 00 06 0D

Main signaling pseudo-header packet IP checksum packets long tail

29 29 30 00 06 0D

Head Command Length pseudo IP Check code tail

29 29 81 00 28    （34Byte） 0D

Head command length pseudo IP Position data Check code tail

Appendix A location data

yymmddhhmmss wwww jjjj ssff st lichen1 lichen2 lichen3 st1st2st3st4 v1v2v3v4v5v6v7v8 yymmddhhmmss: date when the minutes and seconds 

Said date range: Year, the latter two; month, 1-12; date ,1-31 

Time represents the range: hours ,00 --23; minutes ,00 - 59; seconds ,00 - 59 Hours, minutes, seconds are used compressed BCD encoding. 

[For example]: at 10:23:15 on January 1st, 2007 is expressed as: 

07H, 01H, 01H, 10H, 23H, 15H 

 jjjj: Longitude Longitude range: 000 degrees 00.000 minutes - 179 degrees 59.999 minutes; 

 The use of compressed BCD encoding, but the maximum is the sign bit. 

"Positive" means "N", "negative" means "W"; 

 "Points" of the unit are: one-thousandth of points. 

 [For example]: 130 degrees 45.608 minutes west longitude is expressed as:

 (Note: 1 degree = 60 minutes) 93H, 04H, 56H, 08H 

 wwww: Latitude Latitude represents the range: 00 

degrees 00.000 minutes - 89 degrees 59.999 minutes;