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→Codec 8 extended
== <big>Codec 8 extended</big> ==
== <big>Codec 8 Extended</big> ==
*'''Protocols overview'''
Difference between codec8 and codec8 extended
{| class="wikitable"
|-
! style="background: black; color: white;"| !!style="background: black; color: white;"| Codec 8 !!style="background: black; color: white;"| Codec 8 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 || include Includes variable size elements
|}
Table 2. Codec 8 and 8 Extended differences
Main differences between are shown in above table. AVL data element sizes in codec 8 extended protocol was increased to 2 byte length and new variable type added. For more detailed description look in codec 8
and codec 8 extended chapters.
*'''Codec 8 extended protocol sending over TCP'''
'''AVL data packet'''
Below table represents AVL data packet structure.
{| class="wikitable"
|-
! style="background: black; color: white;"|4 zeros !! style="background: black; color: white;"|Data field length !! style="background: black; color: white;"|Codec ID !! style="background: black; color: white;"|Number of
Data 1
!! style="background: black; color: white;"|AVL Data !! style="background: black; color: white;"|Number of
Data 2
!! style="background: black; color: white;"|CRC-16
|-
| 4 Bytes || 4 Bytes || 1 Byte || 1 Byte || 38-768
Bytes
|| 1 Byte || 4 Bytes
|}
Table 3. AVL data packet structure
Number of data – number of encoded data (number of records). Codec ID is constant 0x8E.
Data field length is the length of bytes [codec id, number of data 2]. Number of data 1 should always be equal to number of data 2 byte.
CRC-16 is 4 bytes, but first two are zeroes and last two are CRC-16 calculated for [codec id, number of data
2]
Minimum AVL packet size is 53 bytes (all IO elements disabled).
*'''AVL Data'''