GPS Address Request Packet Description： Users send address request command to terminal first, then terminal will send address request packet to server for address resolution. Terminal forwards the resolved address to user. Terminal Address Request Packet Format Length (Byte) Example Start Bit 2 0x78 0x78 Packet Length 1 Length = Protocol Number + Information Content + Information Serial Number + Error Check Protocol Number 1 0x2A Information Content Date Time 6 to a decimal） Quantity of GPS information satellites 1 The first character is GPS information length，The second character is positioning satellite number（converted to a decimal） Latitude 4 Convert to a decimal and divide 1800000 Longitude 4 Convert to a decimal and divide 1800000 Speed 1 Convert to a decimal Course, Status 2 Convert to binary number of 16 bits and calculate by bits (see the following diagram) Phone Number 21 Phone Number Alarm/Language 2 latter bit 0x01 Chinese 0x02 English Serial Number 2 Serial number of data sent later at each time will be automatically added ‘1’. Error Check 2 Serial Number (including “Packet Length” and “Information Serial Number”) , are values of CRC-ITU. CRC error occur when the received information is calculated, the receiver will ignore and discard the data packet. (See Appendix 1) Stop Bit 2 Fixed value: 0x0D0x0A Example：78 78 2E 2A 0F 0C 1D 07 11 39 CA 02 7A C8 00 0C 46 58 00 00 14 D8 31 32 35 32 30 31 33 35 33 32 31 37 37 30 37 39 00 00 00 00 00 00 01 00 2A 6E CE 0D 0A
Chinese response of server address request packet Length Description Start Bit 2 0x78 0x78 Length of data bit 1 Length = Protocol Number + Information Content + Information Serial Number + Error Check Protocol Number 1 0x17 Information Content Length of Command 1 Server Flag Bit + Length of Command Content Server Flag Bit 4 It is reserved to the identification of the server. ADDRESS 8 Address request code mark（ASCII） && 2 Separator（ASCII） Address Content M Address resolved by server（UNICODE） && 2 Separator（ASCII） Phone Number 21 Request packet number by transmitted by server（ASCII） ## 2 Separator（ASCII） Information Serial Number 2 Serial number of data sent later at each time will be automatically added ‘1’. Check Bit 2 Serial Number (including “Packet Length” and “Information Serial Number”) , are values of CRC-ITU. CRC error occur when the received information is calculated, the receiver will ignore and discard the data packet. (See Appendix 1) Stop Bit 2 Fixed value:0x0D 0x0A Example：78 78 6E 17 68 00 00 00 01 41 44 44 52 45 53 53 26 26 4F 4D 7F 6E 00 3A 5E 7F 4E 1C 77 01 00 2E 60 E0 5D DE 5E 02 00 2E 60 E0 57 CE 53 3A 00 2E 4E 91 5C 71 89 7F 8D EF 00 2E 79 BB 60 E0 5D DE 5E 02 5B 66 59 27 65 59 80 B2 7E A6 00 32 00 35 7C 73 00 2E 26 26 38 36 31 33 34 32 31 36 33 32 36 39 39 00 00 00 00 00 00 00 00 23 23 00 16 C1 EC 0D 0A English response of server address request packet Length Description Start Bit 2 0x79 0x79 Length of data bit 2 Length = Protocol Number + Information Content + Information Serial Number + Error Check Protocol Number 1 0x97 Information Content Length of Command 1 Server Flag Bit + Length of Command Content Server Flag Bit 4 Leave for server identification. ADDRESS 8 Address request code mark（ASCII） && 2 Separator（ASCII）