Codec
Introduction
A codec is a device or computer program for encoding or decoding a digital data stream or signal. Codec is a portmanteau of coder – decoder. A codec encodes a data stream or a signal for transmission and storage, possibly in encrypted form, and the decoder function reverses the encoding for playback or editing.
Below you will see a table of all Codec types with ID’s:
| Codec 8 | Codec 8 Extended | Codec 16 | Codec 12 | Codec 13 | Codec 14 |
|---|---|---|---|---|---|
| 0x08 | 0x8E | 0x10 | 0x0C | 0x0D | 0x0E |
Also, there are using two data transport protocols: TCP and UDP. But it is not important which one will be used in Codec.
Codec for device data sending
In this chapter you will find information about every Codec protocol which are using for device data sending and differences between them.
Codec 8
- Protocol Overview
Codec8 – a main FM device protocol that is used for sending data to server.
- Codec 8 protocol sending over TCP
TCP is a connection-oriented protocol that is used for communication between devices. The workings of this type of protocol is described below in the communication with server section.
- AVL Data Packet
Below table represents AVL Data Packet structure:
| 0x00000000 (Preamble) | Data Field Length | Codec ID | Number of Data 1 | AVL Data | Number of Data 2 | CRC-16 |
|---|---|---|---|---|---|---|
| 4 bytes | 4 bytes | 1 byte | 1 byte | X bytes | 1 byte | 4 bytes |
Preamble – the packet starts with four zero bytes.
Data Field Length – size is calculated starting from Codec ID to Number of Data 2.
Codec ID – in Codec8 it is always 0x08.
Number of Data 1 – a number which defines how many records is in the packet.
AVL Data – actual data in the packet (more information below).
Number of Data 2 – a number which defines how many records is in the packet. This number must be the same as “Number of Data 1”.
CRC-16 – calculated from Codec ID to the Second Number of Data. CRC (Cyclic Redundancy Check) is an error-detecting code using for detect accidental changes to RAW data. For calculation we are using CRC-16/IBM.
Note: for FMB630, FMB640 and FM63XY, minimum AVL record size is 45 bytes (all IO elements disabled). Maximum AVL record size is 255 bytes. Maximum AVL packet size is 512 bytes. For other devices, minimum AVL record size is 45 bytes (all IO elements disabled). Maximum AVL packet size is 1280 bytes.
- AVL Data
Below table represents AVL Data structure.
| Timestamp | Priority | GPS Element | IO Element |
|---|---|---|---|
| 8 bytes | 1 byte | 15 bytes | X bytes |
Timestamp – a difference, in milliseconds, between the current time and midnight, January, 1970 UTC (UNIX time).
Priority – field which define AVL data priority (more information below).
GPS Element – location information of the AVL data (more information below).
IO Element – additional configurable information from device (more information below).
- Priority
Below table represents Priority values. Packet priority depends on device configuration and records sent.
| Priority | |
|---|---|
| 0 | Low |
| 1 | High |
| 2 | Panic |
- GPS element
Below table represents GPS Element structure:
| Longitude | Latitude | Altitude | Angle | Satellites | Speed |
|---|---|---|---|---|---|
| 4 bytes | 4 bytes | 2 bytes | 2 bytes | 1 byte | 2 bytes |
Longitude – east – west position.
Latitude – north – south position.
Altitude – meters above sea level.
Angle – degrees from north pole.
Satellites – number of visible satellites.
Speed – speed calculated from satellites.
Note: If record are without valid coordinates – (there were no GPS fix in the moment of data acquisition) – Longitude, Latitude and Altitude values are last valid fix, and Angle, Satellites and Speed are 0.
Longitude and latitude are integer values built from degrees, minutes, seconds and milliseconds by formula: 
Where:
d – Degrees; m – Minutes; s – Seconds; ms – Milliseconds; p – Precision (10000000)
If longitude is in west or latitude in south, multiply result by –1.
Note:
To determine if the coordinate is negative, convert it to binary format and check the very first bit. If it is 0, coordinate is positive, if it is 1, coordinate is negative.
Example:
Received value: 20 9C CA 80 converted to BIN: 00100000 10011100 11001010 10000000 first bit is 0, which means coordinate is positive converted to DEC: 547146368. For more information see two‘s complement arithmetic.
- IO Element
| Event IO ID | 1 byte | Event IO ID – if data is acquired on event – this field defines which IO property has changed and generated an event. For example, when if Ignition state changed and it generate event, Event IO ID will be 0xEF (AVL ID: 239). If it’s not eventual record – the value is 0. N – a total number of properties coming with record (N = N1 + N2 + N4 + N8). | |
|---|---|---|---|
| N of Total IO | 1 byte | ||
| N1 of One Byte IO | 1 byte | ||
| 1’st IO ID | 1 byte | ||
| 1’st IO Value | 1 byte | ||
| ... | |||
| N1’th IO ID | 1 byte | ||
| N1’th IO Value | 1 byte | ||
| N2 of Two Bytes | 1 byte | ||
| 1’st IO ID | 1 byte | ||
| 1’st IO Value | 2 bytes | ||
| ... | |||
| N2’th IO ID | 1 byte | ||
| N2’th IO Value | 2 bytes | ||
| N4 of Four Bytes | 1 byte | ||
| 1’st IO ID | 1 byte | ||
| 1’st IO Value | 4 bytes | ||
| ... | |||
| N4’th IO ID | 1 byte | ||
| N4’th IO Value | 4 byte | ||
| N8 of Eight Bytes | 1 byte | ||
| 1’st IO ID | 1 byte | ||
| 1’st IO Value | 8 byte | ||
| ... | |||
| N8’IO ID | 1 byte | ||
| N8’IO Value | 8 bytes | ||
- Communication with server
First, when module connects to server, module sends its IMEI. First comes short identifying number of bytes written and then goes IMEI as text (bytes).
For example, IMEI 356307042441013 would be sent as 000F333536333037303432343431303133.
First two bytes denote IMEI length. In this case 0x000F means, that IMEI is 15 bytes long.
After receiving IMEI, server should determine if it would accept data from this module. If yes, server will reply to module 01, if not - 00. Note that confirmation should be sent as binary packet. I.e. 1 byte 0x01 or 0x00.
Then module starts to send first AVL data packet. After server receives packet and parses it, server must report to module number of data received as integer (four bytes).
If sent data number and reported by server doesn’t match module resends sent data.
- Example:
Module connects to server and sends IMEI: 000F333536333037303432343431303133
Server accepts the module:
01
Module sends data packet:
| AVL Data Packet Header | AVL Data Array | CRC-16 |
|---|---|---|
| Four Zero Bytes – 0x00000000,
“AVL Data Array” length – 0x000000FE |
Codec ID – 0x08,
Number of Data – 0x02 |
CRC of “AVL Data Array” |
| 00000000000000FE | 0802...(data elements)...02 | 00008612 |
Server acknowledges data reception (2 data elements): 00000002
- Examples
Hexadecimal stream of AVL Data Packet receiving and response in these examples are given in hexadecimal form. The different fields of packets are separate into different table columns for better readability and some of them are converted to ASCII values for better understanding.
1'st example
Receiving one data record with each element property (1 byte, 2 bytes, 4 byte and 8 byte).
Received data in hexadecimal stream: 000000000000003608010000016B40D8EA30010000000000000000000000000000000105021503010101425E0F01F10000601A014E0000000000000000010000C7CF
Parsed:
| AVL Data Packet | ||
|---|---|---|
| AVL Data Packet Part | HEX Code Part | |
| Zero Bytes | 00 00 00 00 | |
| Data Field Length | 00 00 00 36 | |
| Codec ID | 08 | |
| Number of Data 1 (Records) | 01 | |
| AVL Data | Timestamp | 00 00 01 6B 40 D8 EA 30 (GMT: Monday, June 10, 2019 10:04:46 AM) |
| Priority | 01 | |
| Longitude | 00 00 00 00 | |
| Latitude | 00 00 00 00 | |
| Altitude | 00 00 | |
| Angle | 00 00 | |
| Satellites | 00 | |
| Speed | 00 00 | |
| Event IO ID | 01 | |
| N of Total ID | 05 | |
| N1 of One Byte IO | 02 | |
| 1’st IO ID | 15 (AVL ID: 21, Name: GSM Signal) | |
| 1’st IO Value | 03 | |
| 2’nd IO ID | 01 (AVL ID: 1, Name: DIN1) | |
| 2’nd IO Value | 01 | |
| N2 of Two Bytes IO | 01 | |
| 1’st IO ID | 42 (AVL ID: 66, Name: External Voltage) | |
| 1’st IO Value | 5E 0F | |
| N4 of Four Bytes IO | 01 | |
| 1’st IO ID | F1 (AVL ID: 241, Name: Active GSM Operator) | |
| 1’st IO Value | 00 00 60 1A | |
| N8 of Eight Bytes IO | 01 | |
| 1’st IO ID | 4E (AVL ID: 78, Name: iButton) | |
| 1’st IO Value | 00 00 00 00 00 00 00 00 | |
| Number of Data 2 (Number of Total Records) | 01 | |
| CRC-16 | 00 00 C7 CF | |
Server response: 00000001
2'nd example
Receiving one data record with one or two different element properties (1 byte, 2 byte).
Received data in hexadecimal stream: 000000000000002808010000016B40D9AD80010000000000000000000000000000000103021503010101425E100000010000F22A
Parsed:
| AVL Data Packet | ||
|---|---|---|
| AVL Data Packet Part | HEX Code Part | |
| Zero Bytes | 00 00 00 00 | |
| Data Field Length | 00 00 00 28 | |
| Codec ID | 08 | |
| Number of Data 1 (Records) | 01 | |
| AVL Data | Timestamp | 00 00 01 6B 40 D9 AD 80 (GMT: Monday, June 10, 2019 10:05:36 AM) |
| Priority | 01 | |
| Longitude | 00 00 00 00 | |
| Latitude | 00 00 00 00 | |
| Altitude | 00 00 | |
| Angle | 00 00 | |
| Satellites | 00 | |
| Speed | 00 00 | |
| Event IO ID | 01 | |
| N of Total ID | 03 | |
| N1 of One Byte IO | 02 | |
| 1’st IO ID | 15 (AVL ID: 21, Name: GSM Signal) | |
| 1’st IO Value | 03 | |
| 2’nd IO ID | 01 (AVL ID: 1, Name: DIN1) | |
| 2’nd IO Value | 01 | |
| N2 of Two Bytes IO | 01 | |
| 1’st IO ID | 42 (AVL ID: 66, Name: External Voltage) | |
| 1’st IO Value | 5E 10 | |
| N4 of Four Bytes IO | 00 | |
| N8 of Eight Bytes IO | 00 | |
| Number of Data 2 (Number of Total Records) | 01 | |
| CRC-16 | 00 00 F2 2A | |
Server response: 00000001
3'rd example
Receiving two or more data records with one or more different element properties.
Received data in hexadecimal stream: 000000000000004308020000016B40D57B480100000000000000000000000000000001010101000000000000016B40D5C198010000000000000000000000000000000
101010101000000020000252C
Parsed:
| AVL Data Packet | ||
|---|---|---|
| AVL Data Packet Part | HEX Code Part | |
| Zero Bytes | 00 00 00 00 | |
| Data Field Length | 00 00 00 43 | |
| Codec ID | 08 | |
| Number of Data 1 (Records) | 02 | |
| AVL Data
(1'st record) |
Timestamp | 00 00 01 6B 40 D5 7B 48 (GMT: Monday, June 10, 2019 10:01:01 AM) |
| Priority | 01 | |
| Longitude | 00 00 00 00 | |
| Latitude | 00 00 00 00 | |
| Altitude | 00 00 | |
| Angle | 00 00 | |
| Satellites | 00 | |
| Speed | 00 00 | |
| Event IO ID | 01 | |
| N of Total ID | 01 | |
| N1 of One Byte IO | 01 | |
| 1’st IO ID | 01 (AVL ID: 1, Name: DIN1) | |
| 1’st IO Value | 00 | |
| N2 of Two Bytes IO | 00 | |
| N4 of Four Bytes IO | 00 | |
| N8 of Eight Bytes IO | 00 | |
| AVL Data
(2'nd record) |
Timestamp | 00 00 01 6B 40 D5 C1 98 (GMT: Monday, June 10, 2019 10:01:19 AM) |
| Priority | 01 | |
| Longitude | 00 00 00 00 | |
| Latitude | 00 00 00 00 | |
| Altitude | 00 00 | |
| Angle | 00 00 | |
| Satellites | 00 | |
| Speed | 00 00 | |
| Event IO ID | 01 | |
| N of Total ID | 01 | |
| N1 of One Byte IO | 01 | |
| 1’st IO ID | 01 (AVL ID: 1, Name: DIN1) | |
| 1’st IO Value | 01 | |
| N2 of Two Bytes IO | 00 | |
| N4 of Four Bytes IO | 00 | |
| N8 of Eight Bytes IO | 00 | |
| Number of Data 2 (Number of Total Records) | 02 | |
| CRC-16 | 00 00 25 2C | |
Server response: 00000002
- Codec8 protocol sending over UDP
Codec8 protocol over UDP is a transport layer protocol above UDP/IP to add reliability to plain UDP/IP using acknowledgment packets.
- AVL Data Packet
The packet structure is as follows:
| UDP Datagram | |
|---|---|
| Example | 2 bytes |
| Packet ID | 2 bytes |
| Not Usable Byte | 1 byte |
| Packet Payload | Variable |
Example – packet length (excluding this field) in big ending byte order.
Packet ID – packet ID unique for this channel.
Not Usable Byte – not usable byte.
Packet payload – data payload.
- Acknowledgment packet
Acknowledgment packet should have the same Packet ID as acknowledged data packet and empty Data Payload. Acknowledgement should be sent in binary format.
| Acknowledgment Packet | ||
|---|---|---|
| Packet Length | Packet ID | Not Usable Byte |
| 2 bytes | 2 bytes | 1 byte |
Packet Length – packet length by sending/response data.
Packet ID – same as in acknowledgment packet.
Not Usable Byte – always will be 0x01.
- Sending AVL Packet Payload using UDP channel
Below table represents Sending Packet Payload structure.
| AVL data encapsulated in UDP channel packet | |||
|---|---|---|---|
| AVL Packet ID | IMEI Length | Module IMEI | AVL Data Array |
| 1 byte | 2 bytes | 15 bytes | X bytes |
AVL Packet ID – ID identifying this AVL packet.
IMEI Length – always will be 0x000F.
Module IMEI – IMEI of a sending module encoded the same as with TCP.
AVL Data Array – array of encoded AVL data (same as TCP AVL Data Array).
- Server response Packet Payload using UDP channel
Below table represents Server Response Packet Payload structure.
| Server Response to AVL Data Packet | |
|---|---|
| AVL Packet ID | Number of Accepted AVL Elements |
| 1 byte | 1 byte |
- Communication with server
Module sends UDP channel packet with encapsulated AVL data packet. Server sends UDP channel packet with encapsulated response module validates AVL Packet ID and Number of accepted AVL elements. If server response with valid AVL Packet ID is not received within configured timeout, module can retry sending.
- Example:
Module sends the data:
| UDP Channel Header | AVL Packet Header | AVL Data Array |
|---|---|---|
| Length – 0x00FE,
Packet ID – 0xCAFE |
AVL Packet ID – 0xDD,
IMEI Length – 0x000F |
Codec ID – 0x08,
Number of Data – 0x02 |
| 00FECAFE01 | DD000F3133343536373839303132333435 | 0802…(data elements)…02 |
Server must respond with acknowledgment:
| UDP Channel Header | AVL Packet Acknowledgment |
|---|---|
| Length – 0x0005,
Packet ID – 0xCAFE, Not Usable Byte – 0x01 |
AVL Packet ID – 0xDD,
Number of Accepted Data – 0x02 |
| 0005CAFE01 | DD02 |
- Example
Hexadecimal stream of AVL Data Packet receiving and response in this example are given in hexadecimal form. The different fields of packet are separate into different table columns for better readability and some of them are converted to ASCII values for better understanding.
Received data in hexadecimal stream: 003DCAFE0105000F33353230393330383634303336353508010000016B4F815B30010000000000000000000000000000000103021503010101425DBC000001
Parsed:
| AVL Data Packet | ||
|---|---|---|
| AVL Data Packet Part | HEX Code Part | |
| UDP Channel Header | Length | 00 3D |
| Packet ID | CA FE | |
| Not usable byte | 01 | |
| AVL Packet Header | AVL packet ID | 05 |
| IMEI Length | 00 0F | |
| IMEI | 33 35 32 30 39 33 30 38 36 34 30 33 36 35 35 | |
| AVL Data Array | Codec ID | 08 |
| Number of Data 1 (Records) | 01 | |
| Timestamp | 00 00 01 6B 4F 81 5B 30 (GMT: Thursday, June 13, 2019 6:23:26 AM) | |
| Priority | 01 | |
| Longitude | 00 00 00 00 | |
| Latitude | 00 00 00 00 | |
| Altitude | 00 00 | |
| Angle | 00 00 | |
| Satellites | 00 | |
| Speed | 00 00 | |
| Event IO ID | 01 | |
| N of Total ID | 03 | |
| N1 of One Byte IO | 02 | |
| 1’st IO ID | 15 (AVL ID: 21, Name: GSM Signal) | |
| 1’st IO Value | 03 | |
| 2’nd IO ID | 01 (AVL ID: 1, Name: DIN1) | |
| 2’nd IO Value | 01 | |
| N2 of Two Bytes IO | 01 | |
| 1’st IO ID | 42 (AVL ID: 66, Name: External Voltage) | |
| 1’st IO Value | 5D BC | |
| N4 of Four Bytes IO | 00 | |
| N8 of Eight Bytes IO | 00 | |
| Number of Data 2 (Number of Total Records) | 01 | |
Server response in hexadecimal stream:
0005CAFE010501
Parsed:
| Server Response to AVL Data Packet | ||
|---|---|---|
| Server Response Part | HEX Code Part | |
| UDP Channel Header | Length | 00 05 |
| Packet ID | CA FE | |
| Not usable byte | 01 | |
| AVL Packet Acknowledgment | AVL packet ID | 05 |
| Number of Accepted Data | 01 | |
Codec 8 Extended
- Protocols overview
Codec8 Extended is using for FMBXXX family devices. This protocol looks familiar like Codec8 but they have some differences. Main differences between are shown in below table:
| Codec8 | Codec8 Extended | |
|---|---|---|
| Codec ID | 0x08 | 0x8E |
| AVL Data IO element length | 1 byte | 2 bytes |
| AVL Data IO element total IO count length | 1 byte | 2 bytes |
| AVL Data IO element IO count length | 1 byte | 2 bytes |
| AVL Data IO element AVL ID length | 1 byte | 2 bytes |
| Variable size IO elements | Does not include | Includes variable size elements |
- Codec 8 Extended protocol sending over TCP
- AVL data packet
Below table represents AVL data packet structure:
| 0x00000000 (Preamble) | Data Field Length | Codec ID | Number of Data 1 | AVL Data | Number of Data 2 | CRC-16 |
|---|---|---|---|---|---|---|
| 4 bytes | 4 bytes | 1 byte | 1 byte | X bytes | 1 byte | 4 bytes |
Preamble – the packet starts with four zero bytes.
Data Field Length – size is calculated starting from Codec ID to Number of Data 2.
Codec ID – in Codec8 Extended it is always 0x8E.
Number of Data 1 – a number which defines how many records is in the packet.
AVL Data – actual data in the packet (more information below).
Number of Data 2 – a number which defines how many records is in the packet. This number must be the same as “Number of Data 1”.
CRC-16 – calculated from Codec ID to the Second Number of Data. CRC (Cyclic Redundancy Check) is an error-detecting code using for detect accidental changes to RAW data. For calculation we are using CRC-16/IBM.
Note: for FMB630, FMB640 and FM63XY, minimum AVL packet size is 45 bytes (all IO elements disabled). Maximum AVL packet size is 255 bytes. For other devices, minimum AVL packet size is 45 bytes (all IO elements disabled). Maximum AVL packet size is 1280 bytes.
- AVL Data
Below table represents AVL Data structure:
| Timestamp | Priority | GPS Element | IO Element |
|---|---|---|---|
| 8 bytes | 1 byte | 15 bytes | X bytes |
Timestamp – a difference, in milliseconds, between the current time and midnight, January, 1970 UTC (UNIX time).
Priority – field which define AVL data priority (more information below).
GPS Element – locational information of the AVL data (more information below).
IO Element – additional configurable information from device (more information below).
- Priority
Below table represents Priority values. Packet priority depends on device configuration and records sent.
| Priority | |
|---|---|
| 0 | Low |
| 1 | High |
| 2 | Panic |
- GPS element
Below table represents GPS Element structure:
| Longitude | Latitude | Altitude | Angle | Satellites | Speed |
|---|---|---|---|---|---|
| 4 bytes | 4 bytes | 2 bytes | 2 bytes | 1 byte | 2 bytes |
Longitude – east – west position.
Latitude – north – south position.
Altitude – meters above sea level.
Angle – degrees from north pole.
Satellites – number of visible satellites.
Speed – speed calculated from satellites.
Note: If record are without valid coordinates – (there were no GPS fix in the moment of data acquisition) – Longitude, Latitude and Altitude values are last valid fix, and Angle, Satellites and Speed are 0.
Longitude and latitude are integer values built from degrees, minutes, seconds and milliseconds by formula:
Where:
d – Degrees; m – Minutes; s – Seconds; ms – Milliseconds; p – Precision (10000000)
If longitude is in west or latitude in south, multiply result by –1.
Note:
To determine if the coordinate is negative, convert it to binary format and check the very first bit. If it is 0, coordinate is positive, if it is 1, coordinate is negative.
Example:
Received value: 20 9C CA 80 converted to BIN: 00100000 10011100 11001010 10000000 first bit is 0, which means coordinate is positive converted to DEC: 547146368. For more information see two‘s complement arithmetic.
- IO Element
| Event IO ID | 2 bytes | Event IO ID – if data is acquired on event – this field defines which IO property has changed and generated an event. For example, when if Ignition state changed and it generate event, Event IO ID will be 0x00EF (AVL ID: 239). If it’s not eventual record – the value is 0x0000. N – a total number of properties coming with record (N = N1 + N2 + N4 + N8). | |
|---|---|---|---|
| N of Total IO | 2 bytes | ||
| N1 of One Byte IO | 2 bytes | ||
| 1’st IO ID | 2 bytes | ||
| 1’st IO Value | 1 byte | ||
| ... | |||
| N1’th IO ID | 2 bytes | ||
| N1’th IO Value | 1 byte | ||
| N2 of Two Bytes | 2 bytes | ||
| 1’st IO ID | 2 bytes | ||
| 1’st IO Value | 2 bytes | ||
| ... | |||
| N2’th IO ID | 2 bytes | ||
| N2’th IO Value | 2 bytes | ||
| N4 of Four Bytes | 2 bytes | ||
| 1’st IO ID | 2 bytes | ||
| 1’st IO Value | 4 bytes | ||
| ... | |||
| N4’th IO ID | 2 bytes | ||
| N4’th IO Value | 4 byte | ||
| N8 of Eight Bytes | 2 bytes | ||
| 1’st IO ID | 2 bytes | ||
| 1’st IO Value | 8 byte | ||
| ... | |||
| N8’IO ID | 2 bytes | ||
| N8’IO Value | 8 bytes | ||
| NX of X Byte IO | 2 bytes | ||
| 1’st IO ID | 2 bytes | ||
| 1’st IO Length | 2 bytes | ||
| 1’st IO Value | Defined by lenght | ||
| ... | |||
| NX’th IO ID | 2 bytes | ||
| NX’th Length | 2 bytes | ||
| NX’th Value | Defined by lenght | ||
- Communication with server
Communication with server is the same as with Codec8 protocol, except in Codec8 Extended protocol Codec ID is 0x8E.
- Example:
Module connects to server and sends IMEI: 000F333536333037303432343431303133
Server accepts the module: 01
Module sends data packet:
| AVL Data Packet Header | AVL Data Array | CRC-16 |
|---|---|---|
| Four Zero Bytes – 0x00000000,
“AVL Data Array” length – 0x000000FE |
Codec ID – 0x8E,
Number of Data – 0x02 |
CRC of “AVL Data Array” |
| 00000000000000FE | 8E02...(data elements)...02 | 00008612 |
Server acknowledges data reception (2 data elements): 00000002
- Example
Hexadecimal stream of AVL Data Packet receiving and response in this example are given in hexadecimal form. The different fields of packet are separate into different table columns for better readability and some of them are converted to ASCII values for better understanding.
Received data in hexadecimal stream: 000000000000004A8E010000016B412CEE000100000000000000000000000000000000010005000100010100010011001D00010010015E2C880002000B000000003544C87
A000E000000001DD7E06A00000100002994
Parsed data:
| AVL Data Packet | ||
|---|---|---|
| AVL Data Packet Part | HEX Code Part | |
| Zero Bytes | 00 00 00 00 | |
| Data Field Length | 00 00 00 4A | |
| Codec ID | 8E | |
| Number of Data 1 (Records) | 01 | |
| AVL Data | Timestamp | 00 00 01 6B 41 2C EE 00 (GMT: Monday, June 10, 2019 11:36:32 AM) |
| Priority | 01 | |
| Longitude | 00 00 00 00 | |
| Latitude | 00 00 00 00 | |
| Altitude | 00 00 | |
| Angle | 00 00 | |
| Satellites | 00 | |
| Speed | 00 00 | |
| Event IO ID | 00 01 | |
| N of Total ID | 00 05 | |
| N1 of One Byte IO | 00 01 | |
| 1’st IO ID | 00 01 (AVL ID: 1, Name: DIN1) | |
| 1’st IO Value | 01 | |
| N2 of Two Bytes IO | 00 01 | |
| 1’st IO ID | 00 11 (AVL ID: 17, Name: Axis X) | |
| 1’st IO Value | 00 1D | |
| N4 of Four Bytes IO | 00 01 | |
| 1’st IO ID | 00 10 (AVL ID: 16, Name: Total Odometer) | |
| 1’st IO Value | 01 5E 2C 88 | |
| N8 of Eight Bytes IO | 00 02 | |
| 1’st IO ID | 00 0B (AVL ID: 11, Name: ICCID1) | |
| 1’st IO Value | 00 00 00 00 35 44 C8 7A | |
| 2’nd IO ID | 00 0E (AVL ID: 14, Name: ICCID2) | |
| 2’nd IO Value | 00 00 00 00 1D D7 E0 6A | |
| NX of X Byte IO | 00 00 | |
| Number of Data 2 (Number of Total Records) | 01 | |
| CRC-16 | 00 00 29 94 | |
Server response: 00000001
- Codec8 Extended protocol sending over UDP
- UDP channel protocol
AVL data packet is the same as with Codec8, except Codec ID is changed to 0x8E. AVL Data encoding performed according to Codec8 Extended protocol.
- Communication with server
Module sends UDP channel packet with encapsulated AVL data packet. Server sends UDP channel packet with encapsulated response module validates AVL Packet ID and Number of accepted AVL elements. If server response with valid AVL Packet ID is not received within configured timeout, module can retry sending.
- Example:
Module sends the data:
| UDP Channel Header | AVL Packet Header | AVL Data Array |
|---|---|---|
| Length – 0x00FE,
Packet ID – 0xCAFE |
AVL Packet ID – 0xDD,
IMEI Length – 0x000F |
Codec ID – 0x8E,
Number of Data – 0x02 |
| 00FECAFE01 | DD000F3133343536373839303132333435 | 8E02…(data elements)…02 |
Server must respond with acknowledgment:
| UDP Channel Header | AVL Packet Acknowledgment |
|---|---|
| Length – 0x0005,
Packet ID – 0xCAFE, Not Usable Byte – 0x01 |
AVL Packet ID – 0xDD,
Number of Accepted Data – 0x02 |
| 0005CAFE01 | DD02 |
- Example
Hexadecimal stream of AVL Data Packet receiving and response in this example are given in hexadecimal form. The different fields of packet are separate into different table columns for better readability and some of them are converted to ASCII values for better understanding.
Received data in hexadecimal stream: 005FCAFE0107000F3335323039333038363430333635358E010000016B4F831C680100000000000000000000000000000000010005000100010100010011009D000100
10015E2C880002000B000000003544C87A000E000000001DD7E06A000001
Parsed:
| AVL Data Packet | ||
|---|---|---|
| AVL Data Packet Part | HEX Code Part | |
| UDP Channel Header | Length | 00 5F |
| Packet ID | CA FE | |
| Not usable byte | 01 | |
| AVL Packet Header | AVL packet ID | 05 |
| IMEI Length | 00 0F | |
| IMEI | 33 35 32 30 39 33 30 38 36 34 30 33 36 35 35 | |
| AVL Data Array | Codec ID | 8E |
| Number of Data 1 (Records) | 01 | |
| Timestamp | 00 00 01 6B 4F 83 1C 68 (GMT: Thursday, June 13, 2019 6:25:21 AM) | |
| Priority | 01 | |
| Longitude | 00 00 00 00 | |
| Latitude | 00 00 00 00 | |
| Altitude | 00 00 | |
| Angle | 00 00 | |
| Satellites | 00 | |
| Speed | 00 00 | |
| Event IO ID | 00 01 | |
| N of Total ID | 00 05 | |
| N1 of One Byte IO | 00 01 | |
| 1’st IO ID | 00 01 (AVL ID: 1, Name: DIN1) | |
| 1’st IO Value | 00 01 | |
| N2 of Two Bytes IO | 00 01 | |
| 1’st IO ID | 00 11 (AVL ID: 17, Name: Axis X) | |
| 1’st IO Value | 00 1D | |
| N4 of Four Bytes IO | 00 01 | |
| 1’st IO ID | 00 10 (AVL ID: 16, Name: Total Odometer) | |
| 1’st IO Value | 01 5E 2C 88 | |
| N8 of Eight Bytes IO | 00 02 | |
| 1’st IO ID | 00 0B (AVL ID: 11, Name: ICCID1) | |
| 1’st IO Value | 00 00 00 00 35 44 C8 7A | |
| 2’nd IO ID | 00 0E (AVL ID: 14, Name: ICCID2) | |
| 2’nd IO Value | 00 00 00 00 1D D7 E0 6A | |
| NX of X Byte IO | 00 00 | |
Server response in hexadecimal stream:
0005CAFE010701
Parsed:
| Server Response to AVL Data Packet | ||
|---|---|---|
| Server Response Part | HEX Code Part | |
| UDP Channel Header | Length | 00 05 |
| Packet ID | CA FE | |
| Not usable byte | 01 | |
| AVL Packet Acknowledgment | AVL packet ID | 07 |
| Number of Accepted Data | 01 | |
Codec 16
- Protocol overview
Codec16 is using for FMB630/FM63XY devices. This protocol looks familiar like Codec8 but they have some differences. Main differences between are shown in table below:
| Codec8 | Codec16 | |
|---|---|---|
| Codec ID | 0x08 | 0x10 |
| AVL Data IO element ID event length | 1 byte | 2 bytes |
| AVL Data IO element AVL ID length | 1 byte | 2 bytes |
| Generation Type | Not Using | Is Using |
Note: Codec16 is supported from firmware – 00.03.xx and newer. (FMB630/FM63XY) || AVL ID‘s which are higher than 255 will can be used only in Codec16 protocol.
- Codec 16 protocol sending over TCP
- AVL data packet
Below table represents AVL data packet structure:
| 0x00000000 (Preamble) | Data Field Length | Codec ID | Number of Data 1 | AVL Data | Number of Data 2 | CRC-16 |
|---|---|---|---|---|---|---|
| 4 bytes | 4 bytes | 1 byte | 1 byte | X bytes | 1 byte | 4 bytes |
Preamble – the packet starts with four zero bytes.
Data Field Length – size is calculated starting from Codec ID to Number of Data 2.
Codec ID – in Codec16 it is always 0x10.
Number of Data 1 – a number which defines how many records is in the packet.
AVL Data – actual data in the packet (more information below).
Number of Data 2 – a number which defines how many records is in the packet. This number must be the same as “Number of Data 1”.
CRC-16 – calculated from Codec ID to the Second Number of Data. CRC (Cyclic Redundancy Check) is an error-detecting code using for detect accidental changes to RAW data. For calculation we are using CRC-16/IBM.
Note: for FMB630 and FM63XY, minimum AVL packet size is 45 bytes (all IO elements disabled). Maximum AVL packet size is 255 bytes.
- AVL Data
Below table represents AVL Data structure:
| Timestamp | Priority | GPS Element | IO Element |
|---|---|---|---|
| 8 bytes | 1 byte | 15 bytes | X bytes |
Timestamp – a difference, in milliseconds, between the current time and midnight, January, 1970 UTC (UNIX time).
Priority – field which define AVL data priority (more information below).
GPS Element – location information of the AVL data (more information below).
IO Element – additional configurable information from device (more information below).
- Priority
Below table represents Priority values. Packet priority depends on device configuration and records sent.
| Priority | |
|---|---|
| 0 | Low |
| 1 | High |
| 2 | Panic |
- GPS element
Below table represents GPS Element structure:
| Longitude | Latitude | Altitude | Angle | Satellites | Speed |
|---|---|---|---|---|---|
| 4 bytes | 4 bytes | 2 bytes | 2 bytes | 1 byte | 2 bytes |
Longitude – east – west position.
Latitude – north – south position.
Altitude – meters above sea level.
Angle – degrees from north pole.
Satellites – number of visible satellites.
Speed – speed calculated from satellites.
Note: If record are without valid coordinates – (there were no GPS fix in the moment of data acquisition) – Longitude, Latitude and Altitude values are last valid fix, and Angle, Satellites and Speed are 0.
Longitude and latitude are integer values built from degrees, minutes, seconds and milliseconds by formula:
Where:
d – Degrees; m – Minutes; s – Seconds; ms – Milliseconds; p – Precision (10000000)
If longitude is in west or latitude in south, multiply result by –1.
Note:
To determine if the coordinate is negative, convert it to binary format and check the very first bit. If it is 0, coordinate is positive, if it is 1, coordinate is negative.
Example:
Received value: 20 9C CA 80 converted to BIN: 00100000 10011100 11001010 10000000 first bit is 0, which means coordinate is positive converted to DEC: 547146368. For more information see two‘s complement arithmetic.
- IO Element
| Event IO ID | 2 bytes | Event IO ID – if data is acquired on event – this field defines which IO property has changed and generated an event. For example, when if Ignition state changed and it generate event, Event IO ID will be 0xEF (AVL ID: 239). If it’s not eventual record – the value is 0. Generation type - data event generation type. More information about it you can find here. | |
|---|---|---|---|
| Generation Type | 1 byte | ||
| N of Total IO | 1 byte | ||
| N1 of One Byte IO | 1 byte | ||
| 1’st IO ID | 2 bytes | ||
| 1’st IO Value | 1 byte | ||
| ... | |||
| N1’th IO ID | 2 bytes | ||
| N1’th IO Value | 1 byte | ||
| N2 of Two Bytes | 1 byte | ||
| 1’st IO ID | 2 bytes | ||
| 1’st IO Value | 2 bytes | ||
| ... | |||
| N2’th IO ID | 2 bytes | ||
| N2’th IO Value | 2 bytes | ||
| N4 of Four Bytes | 1 byte | ||
| 1’st IO ID | 2 bytes | ||
| 1’st IO Value | 4 bytes | ||
| ... | |||
| N4’th IO ID | 2 bytes | ||
| N4’th IO Value | 4 byte | ||
| N8 of Eight Bytes | 1 byte | ||
| 1’st IO ID | 2 bytes | ||
| 1’st IO Value | 8 byte | ||
| ... | |||
| N8’IO ID | 2 bytes | ||
| N8’IO Value | 8 bytes | ||
- Generation type
| Value | Record Created |
|---|---|
| 0 | On Exit |
| 1 | On Entrance |
| 2 | On Both |
| 3 | Reserved |
| 4 | Hysteresis |
| 5 | On Change |
| 6 | Eventual |
| 7 | Periodical |
- Communication with server
Communication with server is the same as with Codec8 protocol, except in Codec16 protocol Codec ID is 0x10 and has generation type.
- Example:
Module connects to server and sends IMEI: 000F333536333037303432343431303133
Server accepts the module: 01
Module sends data packet:
| AVL Data Packet Header | AVL Data Array | CRC-16 |
|---|---|---|
| Four Zero Bytes – 0x00000000,
“AVL Data Array” length – 0x000000FE |
Codec ID – 0x10,
Number of Data – 0x02 |
CRC of “AVL Data Array” |
| 00000000000000FE | 1002...(data elements)...02 | 00008612 |
Server acknowledges data reception (2 data elements): 00000002
- Example
Hexadecimal stream of AVL Data Packet receiving and response in this example are given in hexadecimal form. The different fields of packet are separate into different table columns for better readability and some of them are converted to ASCII values for better understanding.
Received data in hexadecimal stream: 000000000000005F10020000016BDBC7833000000000000000000000000000000000000B05040200010000030002000B00270042563A00000000016BDBC78718
00000000000000000000000000000000000B05040200010000030002000B00260042563A00000200005FB3
Parsed data:
| AVL Data Packet | ||
|---|---|---|
| AVL Data Packet Part | HEX Code Part | |
| Zero Bytes | 00 00 00 00 | |
| Data Field Length | 00 00 00 5F | |
| Codec ID | 10 | |
| Number of Data 1 (Records) | 02 | |
| AVL Data
(1'st record) |
Timestamp | 00 00 01 6B DB C7 83 30 (GMT: Wednesday, July 10, 2019 12:06:54 PM) |
| Priority | 01 | |
| Longitude | 00 00 00 00 | |
| Latitude | 00 00 00 00 | |
| Altitude | 00 00 | |
| Angle | 00 00 | |
| Satellites | 00 | |
| Speed | 00 00 | |
| Event IO ID | 00 0B | |
| Generation Type | 05 | |
| N of Total ID | 04 | |
| N1 of One Byte IO | 02 | |
| 1’st IO ID | 00 01 (AVL ID: 1, Name: DIN1) | |
| 1’st IO Value | 00 | |
| 2’nd IO ID | 00 03 (AVL ID: 3, Name: DIN3) | |
| 2’nd IO Value | 00 | |
| N2 of Two Bytes IO | 02 | |
| 1’st IO ID | 00 0B (AVL ID: 11, Name: ICCID1) | |
| 1’st IO Value | 00 27 | |
| 2’nd IO ID | 00 42 (AVL ID: 66, Name: External Voltage) | |
| 2’nd IO Value | 56 3A | |
| N4 of Four Bytes IO | 00 | |
| N8 of Eight Bytes IO | 00 | |
| AVL Data
(2'nd record) |
Timestamp | 00 00 01 6B DB C7 87 18 (GMT: Wednesday, July 10, 2019 12:06:55 PM) |
| Priority | 01 | |
| Longitude | 00 00 00 00 | |
| Latitude | 00 00 00 00 | |
| Altitude | 00 00 | |
| Angle | 00 00 | |
| Satellites | 00 | |
| Speed | 00 00 | |
| Event IO ID | 00 0B | |
| Generation Type | 05 | |
| N of Total ID | 04 | |
| N1 of One Byte IO | 02 | |
| 1’st IO ID | 00 01 (AVL ID: 1, Name: DIN1) | |
| 1’st IO Value | 00 | |
| 2’nd IO ID | 00 03 (AVL ID: 3, Name: DIN3) | |
| 2’nd IO Value | 00 | |
| N2 of Two Bytes IO | 02 | |
| 1’st IO ID | 00 0B (AVL ID: 11, Name: ICCID1) | |
| 1’st IO Value | 00 26 | |
| 2’nd IO ID | 00 42 (AVL ID: 66, Name: External Voltage) | |
| 2’nd IO Value | 56 3A | |
| N4 of Four Bytes IO | 00 | |
| N8 of Eight Bytes IO | 00 | |
| Number of Data 2 (Number of Total Records) | 02 | |
| CRC-16 | 00 00 5F B3 | |
Server response: 00000002
- Codec16 protocol sending over UDP
- UDP channel protocol
AVL data packet is the same as with Codec8, except Codec ID is changed to 0x10. AVL Data encoding performed according to Codec16 protocol.
- Communication with server
Module sends UDP channel packet with encapsulated AVL data packet. Server sends UDP channel packet with encapsulated response module validates AVL Packet ID and Number of accepted AVL elements. If server response with valid AVL Packet ID is not received within configured timeout, module can retry sending.
- Example:
Module sends the data:
| UDP Channel Header | AVL Packet Header | AVL Data Array |
|---|---|---|
| Length – 0x00FE,
Packet ID – 0xCAFE |
AVL Packet ID – 0xDD,
IMEI Length – 0x000F |
Codec ID – 0x10,
Number of Data – 0x02 |
| 00FECAFE01 | DD000F3133343536373839303132333435 | 1002…(data elements)…02 |
Server must respond with acknowledgment:
| UDP Channel Header | AVL Packet Acknowledgment |
|---|---|
| Length – 0x0005,
Packet ID – 0xCAFE, Not Usable Byte – 0x01 |
AVL Packet ID – 0xDD,
Number of Accepted Data – 0x02 |
| 0005CAFE01 | DD02 |
- Example
Hexadecimal stream of AVL Data Packet receiving and response in this example are given in hexadecimal form. The different fields of packet are separate into different table columns for better readability and some of them are converted to ASCII values for better understanding.
Received data in hexadecimal stream: 015BCAFE0101000F33353230393430383532333135393210070000015117E40FE80000000000000000000000000000000000EF05050400010000030000B4000
0EF01010042111A000001
Parsed:
| AVL Data Packet | ||
|---|---|---|
| AVL Data Packet Part | HEX Code Part | |
| UDP Channel Header | Length | 01 5B |
| Packet ID | CA FE | |
| Not usable byte | 01 | |
| AVL Packet Header | AVL packet ID | 07 |
| IMEI Length | 00 0F | |
| IMEI | 33 35 32 30 39 34 30 38 35 32 33 31 35 39 32 | |
| AVL Data Array | Codec ID | 10 |
| Number of Data 1 (Records) | 01 | |
| Timestamp | 00 00 01 51 17 E4 0F E8 (GMT: Wednesday, November 18, 2015 12:00:01 AM) | |
| Priority | 00 | |
| Longitude | 00 00 00 00 | |
| Latitude | 00 00 00 00 | |
| Altitude | 00 00 | |
| Angle | 00 00 | |
| Satellites | 00 | |
| Speed | 00 00 | |
| Event IO ID | 00 EF | |
| Generation type | 05 | |
| N of Total ID | 05 | |
| N1 of One Byte IO | 04 | |
| 1’st IO ID | 00 01 (AVL ID: 1, Name: DIN1) | |
| 1’st IO Value | 00 | |
| 2’nd IO ID | 00 03 (AVL ID: 3, Name: DIN3) | |
| 2’nd IO Value | 00 | |
| 3’rd IO ID | 00 B4 (AVL ID: 180, Name: DOUT2) | |
| 3’rd IO Value | 00 | |
| 4’th IO ID | 00 EF (AVL ID: 239, Name: Ignition) | |
| 4’th IO Value | 00 | |
| N2 of Two Bytes IO | 01 | |
| 1’st IO ID | 42 (AVL ID: 66, Name: External Voltage) | |
| 1’st IO Value | 11 1A | |
| N4 of Four Bytes IO | 00 | |
| N8 of Eight Bytes IO | 00 | |
| Number of Data 2 (Number of Total Records) | 01 | |
Server response in hexadecimal stream:
0005CAFE010701
Parsed:
| Server Response to AVL Data Packet | ||
|---|---|---|
| Server Response Part | HEX Code Part | |
| UDP Channel Header | Length | 00 05 |
| Packet ID | CA FE | |
| Not usable byte | 01 | |
| AVL Packet Acknowledgment | AVL packet ID | 07 |
| Number of Accepted Data | 01 | |
Differences between Codec 8, Codec 8 Extended and Codec 16
In the table below you will see differences between Codec8, Codec8 Extended and Codec16.
| Codec8 | Codec8 Extended | Codec16 | |
|---|---|---|---|
| Codec ID | 0x08 | 0x8E | 0x10 |
| AVL Data IO element length | 1 byte | 2 bytes | 2 bytes |
| AVL Data IO element total IO count length | 1 byte | 2 bytes | 2 bytes |
| Generation Type | Not Using | Not Using | Is Using |
| AVL Data IO element IO count length | 1 byte | 2 bytes | 1 byte |
| AVL Data IO element AVL ID length | 1 byte | 2 bytes | 2 bytes |
| Variable size IO elements | Does not include | Includes variable size elements | Does not include |
Codec for communication over GPRS messages
In this chapter you will find information about every Codec protocol which are using for communication over GPRS messages and differences between them.
Codec 12
- About Codec12
Codec12 is the original and main Teltonika protocol for device-server communication over GPRS messages. Codec12 GPRS commands can be used for sending configuration, debug, digital outputs control commands or other (special purpose command on special firmware versions). This protocol is also necessary for using FMB630/FM6300/FM5300/FM5500/FM4200 features like: Garmin, LCD communication, COM TCP Link Mode.
- FM firmware requirements
Supported GPRS commands on each device depending on the firmware version. For available GPRS commands on each device, please refer to the table below.
| Device | SMS over GPRS via TCP | SMS over GPRS via UDP |
|---|---|---|
| FM36YX | Available in base firmware | Since base firmware 01.06.01 |
| FM63YX | Available in base firmware | Since base firmware 00.02.19 |
| FMB, FMC, FMM, FMU family devices (exclude FMB6YX, FMC640, FMM640) | Available in base firmware | Available in base firmware |
| FMB6YX | Available in base firmware | Since base firmware 00.02.19 |
| FMC640, FMM640 | Available in base firmware | Available in base firmware |
Note: “SMS over GPRS” means that all standard SMS commands text can be sent to the device via GPRS in Codec12 format.
Note: UDP commands are sent the same exact way as TCP commands.
- GPRS command session
The following figure shows how the GRPS command session is started over TCP. 
First, the Teltonika device opens the GPRS session and sends AVL data to the server (refer device protocols). Once all records are sent and correct sent data array acknowledgment is received by device then GPRS commands in Hex can be sent to the device.
The ACK (acknowledge of IMEI from server) is a one-byte constant 0x01. The acknowledgment of each data array send from the device is four bytes integer – the number of records received.
Note, that the GPRS session should remain active between device and server, while GPRS commands are sent. For this reason, active datalink timeout (global parameters in device configuration) is recommended to be set to 259200 (maximum value).
- General Codec12 message structure
The following diagram shows basic structure of Codec12 messages.
Command message structure:
| 0x00000000 (Preamble) | Data Size | Codec ID | Command Quantity 1 | Type (0x05) | Command Size | Command | Command Quantity 2 | CRC-16 |
|---|---|---|---|---|---|---|---|---|
| 4 bytes | 4 bytes | 1 byte | 1 byte | 1 byte | 4 bytes | X bytes | 1 byte | 4 bytes |
Response message structure:
| 0x00000000 (Preamble) | Data Size | Codec ID | Response Quantity 1 | Type (0x06) | Response Size | Response | Response Quantity 2 | CRC-16 |
|---|---|---|---|---|---|---|---|---|
| 4 bytes | 4 bytes | 1 byte | 1 byte | 1 byte | 4 bytes | X bytes | 1 byte | 4 bytes |
Preamble - the packet starts with four zero bytes.
Data Size - size is calculated from Codec ID field to the second command or response quantity field.
Codec ID - in Codec12 it is always 0x0C.
Command/Response Quantity 1 - it is ignored when parsing the message.
Type - it can be 0x05 to denote command or 0x06 to denote response.
Command/Response Size – command or response length.
Command/Response – command or response in HEX.
Command/Response Quantity 2 - a byte which defines how many records (commands or responses) is in the packet. This byte will not be parsed but it’s recommended that it should contain same value as Command/Response Quantity 1.
CRC-16 – calculated from Codec ID to the Command Quantity 2. CRC (Cyclic Redundancy Check) is an error-detecting code using for detect accidental changes to RAW data. For calculation we are using CRC-16/IBM.
Note that difference between commands and responses is message type field: 0x05 means command and 0x06 means response.
- Command coding table
Command has to be converted from ASCII characters (char) to hexadecimal (HEX): 
- Command parsing example
Hexadecimal stream of command and answer in this example is given in hexadecimal form. The different fields of the message are separated into different table columns for better readability and understanding.
- GPRS commands examples
Hexadecimal stream of GPRS command and answer in these examples are given in hexadecimal form. The different fields of messages are separate into different table columns for better readability and some of them are converted to ASCII values for better understanding.
1'st example: Sending getinfo SMS command via GPRS Codec12
Server request in hexadecimal stream: 000000000000000F0C010500000007676574696E666F0100004312
Parsed:
| Server Command | |
|---|---|
| Server Command Part | HEX Code Part |
| Zero Bytes | 00 00 00 00 |
| Data Size | 00 00 00 0F |
| Codec ID | 0C |
| Command Quantity 1 | 01 |
| Command Type | 05 |
| Command Size | 00 00 00 07 |
| Command | 67 65 74 69 6E 66 6F |
| Command Quantity 2 | 01 |
| CRC-16 | 00 00 43 12 |
Note that Server Command converted from HEX to ASCII means getinfo
Device response in hexadecimal stream: 00000000000000900C010600000088494E493A323031392F372F323220373A3232205254433A323031392F372F323220373A3533205253543A32204552523A
312053523A302042523A302043463A302046473A3020464C3A302054553A302F302055543A3020534D533A30204E4F4750533A303A3330204750533A312053
41543A302052533A332052463A36352053463A31204D443A30010000C78F
Parsed:
| Device Answer | |
|---|---|
| Device Answer Part | HEX Code Part |
| Zero Bytes | 00 00 00 00 |
| Data Size | 00 00 00 90 |
| Codec ID | 0C |
| Response Quantity 1 | 01 |
| Response Type | 06 |
| Response Size | 00 00 00 88 |
| Response | 49 4E 49 3A 32 30 31 39 2F 37 2F 32 32 20 37 3A 32 32 20 52 54 43 3A 32 30 31 39 2F 37 2F 32 32 20 37 3A 35 33 20 52 53 54 3A 32 20 45 52 52 3A 31 20 53 52 3A 30 20 42 52 3A 30 20 43 46 3A 30 20 46 47 3A 30 20 46 4C 3A 30 20 54 55 3A 30 2F 30 20 55 54 3A 30 20 53 4D 53 3A 30 20 4E 4F 47 50 53 3A 30 3A 33 30 20 47 50 53 3A 31 20 53 41 54 3A 30 20 52 53 3A 33 20 52 46 3A 36 35 20 53 46 3A 31 20 4D 44 3A 30 |
| Response Quantity 2 | 01 |
| CRC-16 | 00 00 C7 8F |
Note that Device Response converted from HEX to ASCII means:
INI:2019/7/22 7:22 RTC:2019/7/22 7:53 RST:2 ERR:1 SR:0 BR:0 CF:0 FG:0 FL:0 TU:0/0 UT:0 SMS:0 NOGPS:0:30 GPS:1 SAT:0 RS:3 RF:65 SF:1 MD:0
2'nd example: Sending getio SMS command via GPRS Codec12
Server request in hexadecimal stream: 000000000000000D0C010500000005676574696F01000000CB
Parsed:
| Server Command | |
|---|---|
| Server Command Part | HEX Code Part |
| Zero Bytes | 00 00 00 00 |
| Data Size | 00 00 00 0D |
| Codec ID | 0C |
| Command Quantity 1 | 01 |
| Command Type | 05 |
| Command Size | 00 00 00 05 |
| Command | 67 65 74 69 6F |
| Command Quantity 2 | 01 |
| CRC-16 | 00 00 00 CB |
Note that Server Command converted from HEX to ASCII means getio
Device response in hexadecimal stream: 00000000000000370C01060000002F4449313A31204449323A30204449333A302041494E313A302041494E323A313639323420444F313A3020444F323A3101000066E3
Parsed:
| Device Answer | |
|---|---|
| Device Answer Part | HEX Code Part |
| Zero Bytes | 00 00 00 00 |
| Data Size | 00 00 00 37 |
| Codec ID | 0C |
| Response Quantity 1 | 01 |
| Response Type | 06 |
| Response Size | 00 00 00 2F |
| Response | 44 49 31 3A 31 20 44 49 32 3A 30 20 44 49 33 3A 30 20 41 49 4E 31 3A 30 20 41 49 4E 32 3A 31 36 39 32 34 20 44 4F 31 3A 30 20 44 4F 32 3A 31 |
| Response Quantity 2 | 01 |
| CRC-16 | 00 00 66 E3 |
Note that Device Response converted from HEX to ASCII means:
DI1:1 DI2:0 DI3:0 AIN1:0 AIN2:16924 DO1:0 DO2:1
- Communication with server
The GSM/GPRS commands can be sent from a terminal program. We recommend to use Hercules (in TCP server mode). Simply write command as explained below into Hercules Send field, check HEX box and click Send button. Note that the TCP server must be listening on specified port (see Port field and Listen button below).
- FMXX and Codec12 functionality
- Garmin
All information is provided in “FMXX and Garmin development.pdf” document.
- COM TCP Link Mode
All information is provided in “FMxx TCP Link mode test instructions.pdf” document.
Codec 13
- About Codec13
Codec13 is original Teltonika protocol for device-server communication over GPRS messages. This protocol is necessary for using following FM features: COM TCP Link Mode (binary/ASCII/binary buffered/ASCII buffered) if message timestamp parameter is enabled in device configuration. Codec13 messages are one way only (Device → Server sending).
- General Codec13 message structure
The following diagram shows basic structure of Codec 13 messages:
| 0x00000000 (Preamble) | Data Size | Codec ID | Response Quantity 1 | Type | Response Size | Timestamp | Response | Response Quantity 2 | CRC-16 |
|---|---|---|---|---|---|---|---|---|---|
| 4 bytes | 4 bytes | 1 byte | 1 byte | 1 byte | 4 bytes | 4 bytes | X bytes | 1 byte | 4 bytes |
Preamble – the packet starts with preamble field (four zero bytes).
Data Size – size is calculated from Codec ID field to the second Response Quantity field.
Codec ID – in Codec13 it is always 0x0D.
Response Quantity 1 – 0x01, it is ignored when parsing the message.
Response Type – it is always 0x06 since the packet is direction is FM->Server.
Response Size – response size field includes size of timestamp too, so it is equal to size of payload + size of timestamp.
Timestamp – a difference, in seconds, between the current time and midnight, January, 1970 UTC (UNIX time).
Response – actual received data.
Response Quantity 2 – a byte which defines how many records (responses) is in the packet. This byte will not be parsed but it’s recommended that it should contain same value as Response Quantity 1.
CRC-16 – calculated from Codec ID to the Second Number of Data. CRC (Cyclic Redundancy Check) is an error-detecting code using for detect accidental changes to RAW data. For calculation we are using CRC-16/IBM.
Note: Codec13 packets are used only when “Message Timestamp” parameter in RS232 settings is enabled.
- Command parsing example
Hexadecimal stream of GPRS command in this example is given in hexadecimal form. The different fields of message are separate into different table columns for better readability and some of them are converted to ASCII values for better understanding.
Receiving "hello lets test" SMS response via GPRS Codec13
Hexadecimal stream: 000000000000001D0D01060000001564E8328168656C6C6F206C65747320746573740D0A0100003548
Parsed:
| Device answer | |
|---|---|
| Device answer part | HEX Code Part |
| Zero Bytes | 00 00 00 00 |
| Data Size | 00 00 00 1D |
| Codec ID | 0D |
| Response Quantity 1 | 01 |
| Response Type | 06 |
| Response Size | 00 00 00 15 |
| Timestamp | 64 E8 32 81 |
| Response | 68 65 6C 6C 6F 20 6C 65 74 73 20 74 65 73 74 0D 0A |
| Response Quantity 2 | 01 |
| CRC-16 | 00 00 35 48 |
Note that Server Response converted from HEX to ASCII means "hello lets test"
Codec 14
- About Codec14
Codec14 is original Teltonika protocol for device-server communication over GPRS messages and it is based on Codec12 protocol.
Main difference of Codec14 is that, device will answer to GPRS command if device physical IMEI number matches specified IMEI number in GPRS command.
Codec14 GPRS commands can be used for sending configuration, debug, digital outputs control commands or other (special purpose command on special firmware versions).
- FMB firmware requirements
Implemented in base firmware from FMB.Ver.03.25.04.Rev.00 and newer.
- General Codec14 message structure
The following diagram shows basic structure of Codec14 messages.
Command message structure
| 0x00000000 (preamble) | Data size | 0x0E (Codec ID) | Command quantity | 0x05 (Message type) |
Command size + IMEI size (8 bytes) | IMEI (HEX) | Command | Command quantity | CRC-16 |
|---|---|---|---|---|---|---|---|---|---|
| 4 bytes | 4 bytes | 1 bytes | 1 bytes | 1 bytes | 4 bytes | 8 bytes | X bytes | 1 bytes | 4 bytes |
Response message structure
| 0x00000000 (preamble) | Data size | 0x0E (Codec ID) | Response quantity | 0x06 / 0x11 (Message type) | Response size + IMEI size (8 bytes) | IMEI (HEX) | Response | Response quantity | CRC-16 |
|---|---|---|---|---|---|---|---|---|---|
| 4 bytes | 4 bytes | 1 bytes | 1 bytes | 1 bytes | 4 bytes | 8 bytes | X bytes | 1 bytes | 4 bytes |
Preamble – the packet starts with four zero bytes.
Data Size – size is calculated from Codec ID field to the second command or response quantity field.
Codec ID – in Codec14 it is always 0x0E.
Command/Response Quantity 1 – it is ignored when parsing the message.
Type – if it is request command from server it has to contain 0x05. The response type field will contain 0x06 if it’s ACK or 0x11 if it’s nACK.
Explanation: If command message IMEI is equal to actual device IMEI, received command will be executed and response will be sent with ACK (0x06) message type field value. If command message IMEI doesn’t match actual device IMEI, received command won’t be executed and response to server will be sent with nACK (0x11) message type field value.
Command/Response Size – command or response length.
Note: make sure that size is IMEI size 8 + actual command size. Minimal value is 8 because Codec14 always contain IMEI and it’s 8 bytes.
IMEI (HEX) – it is send as HEX value. Example if device IMEI is 123456789123456 then IMEI data field will contain 0x0123456789123456 value.
Command/Response – command or response in HEX.
Command/Response Quantity 2 - a byte which defines how many records (commands or responses) is in the packet. This byte will not be parsed but it’s recommended that it should contain same value as Command/Response Quantity 1.
CRC-16 – calculated from Codec ID to the Second Number of Data. CRC (Cyclic Redundancy Check) is an error-detecting code using for detect accidental changes to RAW data. For calculation we are using CRC-16/IBM.
- GPRS in Codec14 examples
Hexadecimal stream of GPRS command and answer in this example are given in hexadecimal form. The different fields of message are separate into different table columns for better readability and some of them are converted to ASCII values for better understanding.
Sending getver SMS command via GPRS Codec14:
Server requests in Hexadecimal stream: 00000000000000160E01050000000E0352093081452251676574766572010000D2C1
Parsed:
| Server Command | |
|---|---|
| Server Command Part | HEX Code Part |
| Zero Bytes | 00 00 00 00 |
| Data Size | 00 00 00 16 |
| Codec ID | 0E |
| Command Quantity 1 | 01 |
| Command Type | 05 |
| Command Size | 00 00 00 0E |
| IMEI | 03 52 09 30 81 45 22 51 |
| Command | 67 65 74 76 65 72 |
| Command Quantity 2 | 01 |
| CRC-16 | 00 00 D2 C1 |
Note that Server Command converted from HEX to ASCII means getver
Device ACK response in hexadecimal stream: 00000000000000AB0E0106000000A303520930814522515665723A30332E31382E31345F3034204750533A41584E5F352E31305F333333332048773A464D42313230
204D6F643A313520494D45493A33353230393330383134353232353120496E69743A323031382D31312D323220373A313320557074696D653A3137323334204D4143
3A363042444430303136323631205350433A312830292041584C3A30204F42443A3020424C3A312E362042543A340100007AAE
Parsed:
| Device Answer | |
|---|---|
| Device Answer Part | HEX Code Part |
| Zero Bytes | 00 00 00 00 |
| Data Size | 00 00 00 37 |
| Codec ID | 0E |
| Response Quantity 1 | 01 |
| Response Type | 06 |
| Response Size | 00 00 00 A3 |
| IMEI | 03 52 09 30 81 45 22 51 |
| Response | 56 65 72 3A 30 33 2E 31 38 2E 31 34 5F 30 34 20 47 50 53 3A 41 58 4E 5F 35 2E 31 30 5F 33 33 33 33 20 48 77 3A 46 4D 42 31 32 30 20 4D 6F 64 3A 31 35 20 49 4D 45 49 3A 33 35 32 30 39 33 30 38 31 34 35 32 32 35 31 20 49 6E 69 74 3A 32 30 31 38 2D 31 31 2D 32 32 20 37 3A 31 33 20 55 70 74 69 6D 65 3A 31 37 32 33 34 20 4D 41 43 3A 36 30 42 44 44 30 30 31 36 32 36 31 20 53 50 43 3A 31 28 30 29 20 41 58 4C 3A 30 20 4F 42 44 3A 30 20 42 4C 3A 31 2E 36 20 42 54 3A 34 |
| Response Quantity 2 | 01 |
| CRC-16 | 00 00 7A AE |
Note that Device Response converted from HEX to ASCII means:
Ver:03.18.14_04 GPS:AXN_5.10_3333 Hw:FMB120 Mod:15 IMEI:352093081452251 Init:2018-11-22 7:13 Uptime:17234 MAC:60BDD0016261 SPC:1(0) AXL:0 OBD:0 BL:1.6 BT:4
Device nACK response in hexadecimal stream: 00000000000000100E011100000008035209308145246801000032AC
Parsed:
| Device Answer | |
|---|---|
| Device Answer Part | HEX Code Part |
| Zero Bytes | 00 00 00 00 |
| Data Size | 00 00 00 10 |
| Codec ID | 0E |
| Response Quantity 1 | 01 |
| Response Type | 11 |
| Response Size | 00 00 00 08 |
| IMEI | 03 52 09 30 81 45 24 68 |
| Response Quantity 2 | 01 |
| CRC-16 | 00 00 32 AC |
Differences between Codec 12, Codec 13 and Codec 14
In the table below you will see differences between Codec12, Codec13 and Codec14.
| Codec12 | Codec13 | Codec14 | |
|---|---|---|---|
| Communication | Server ⇄ Device Communication | One-way (Device → Server communication) | Server ⇄ Device Communication |
| Codec ID | 0x0C | 0x0D | 0x0E |
| command message type | 0x05 | - | 0x05 |
| Response Message Type | 0x06 | 0x06 | 0x06 (if it is ACK) or 0x11 (if it is nACK) |
| Command / Response size | Command/Response | Only Response | Command/Response + IMEI |
| Timestamp | Not Using | Is Using | Not Using |
| IMEI | Not Using | Not Using | Is Using |
24 Position SMS Data Protocol
24-hour SMS is usually sent once every day and contains GPS data of last 24 hours. TP-DCS field of this SMS should indicate that message contains 8-bit data (i.e. TP-DCS can be 0x04).
Note, that 24 position data protocol is used only with subscribed SMS. Event SMS use standard AVL data protocol.
- Encoding
To be able to compress 24 GPS data entries into one SMS (140 octets), the data is encoded extensively using bit fields. Data packet can be interpreted as a bit stream, where all bits are numbered as follows:
| Byte 1 | Byte 2 | Byte 3 | Byte 4 ... |
|---|---|---|---|
| Bits 0 - 7 | Bits 8 - 15 | Bits 16 - 24 | Bits 25 - ... |
Bits in a byte are numbered starting from least significant bit. A field of 25 bits would consist of bits 0 to 24 where 0 is the least significant bit and bit 24 – most significant bit.
- Structure
Below in the tables you will see SMS Data Structure:
| SMS Data Structure | ||
|---|---|---|
| 8 | Codec ID | Codec ID = 4 (0x04) |
| 35 | Timestamp | Time corresponding to the first (oldest) GPS data element, represented in seconds elapsed from 2000.01.01 00:00 EET. |
| 5 | ElementCount | Number of GPS data elements |
| SMS Data Structure | |||
|---|---|---|---|
| ElementCount * | GPSDataElement | GPS data elements | |
| Byte - align padding | Padding bits to align to 8 - bits boundary represented in seconds elapsed from 2000.01.01 00:00 EET. | ||
| 64 | IMEI | IMEI of sending device as 8 byte long integer | |
The time of only the first GPS data element is specified in Timestamp field. Time corresponding to each further element can be computed as elementTime = Timestamp + (1 hour * elementNumber).
| GPS Data Element | ||||
|---|---|---|---|---|
| Size (bits) | Field | Description | ||
| 1 | ValidElement | ValidElement = 1 – there is a valid Gps Data Element following,
ValidElement = 0 – no element at this position | ||
| ValidElement == 1 | 1 | DifferentialCoords | Format of following data | |
| DifferentialCoords == 1 | 14 | LongitudeDiff | Difference from previous element‘s longitude.
LongitudeDiff = prevLongitude – Longitude + 213 – 1 | |
| 14 | LatitudeDiff | Difference from previous element‘s latitude
LatitudeDiff = prevLatitude – Latitude + 213 – 1 | ||
| DifferentialCoords == 0 | 21 | Longitude | Longitude = {(LongDegMult + 18 * 108) * (221 – 1)} over {36*108} | |
| 20 | Latitude | Latitude = (LatDegMult + 9*108) * (220 – 1) over {18*108} | ||
| 8 | Speed | Speed in km/h | ||
Longitude - longitude field value of GPSDataElement
Latitude - latitude field value of GPSDataElement
LongDegMult - longitude in degrees multiplied by 107 (integer part)
LatDegMult - latitude in degrees multiplied by 107 (integer part)
prevLongitude - longitude field value of previous GPSDataElemen
prevLatitude - latitude field value of previous GPSDataElement
- Decoding GPS position
When decoding GPS data with DifferentialCoords = 1, Latitude and Longitude values can be computed as follows: Longitude = prevLongitude – LongitudeDiff + 213 – 1, Latitude = prevLatitude – LatitudeDiff + 213 – 1.
If there were no previous non-differential positions, differential coordinates should be computed assuming prevLongitude = prevLatitude = 0.
When Longitude and Latitude values are known, longitude and latitude representation in degrees can be computed as follows:
- SMS Events
When Configured to generate SMS event user will get this SMS upon event:
<Year/Month/Day> <Hour:Minute:Second> P:<profile_nr> <SMS Text> Val:<Event Value> Lon:<longitude> Lat:<latitude> Q:<HDOP>
Example:
2016./04/11 12:00:00 P:3 Digital Input 1 Val:1 Lon:51.12258 Lat: 25.7461 Q:0.6
Sending data using SMS
This type data sending is using for FMBXXX devices which can be configured in SMS Data Sending settings.
- Data sending via SMS
AVL data or events can be sent encapsulated in binary SMS. TP-DCS field of these SMS should indicate that message contains 8-bit data (for example: TP-DCS can be 0x04).
| SMS data (TP-UD) | |
|---|---|
| AVL data array | IMEI |
| X bytes | 8 bytes |
AVL data array – array of encoded AVL data.
IMEI – IMEI of sending module encoded as a big endian 8 byte long number.
CRC-16
CRC (Cyclic Redundancy Check) is an error-detecting code using for detect accidental changes to RAW data. The algorithm how to calculate CRC-16 (also known as CRC-16/IBM) you will find below. 