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− | == <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''' |