Becker BD406 - Communication Description; Figure 32: Target Status Protocol - Packet Description

Becker Avionics
Installation and Operation
Targets Status Protocol - IF3 Interface
DV16401.03 Issue 04 May 2021 BD406/PBD406 75
Communication Description
Packet Description
• All bytes have 8-bit data.
• Bits are numerated from 0 (bit 0 is least significant bit - LSB).
• Bytes are numerated from 0.
• Byte 0 is the first byte in the sequence.
• The smallest information interchanged through a physical channel is a byte.
• Bytes are grouped into blocks called packet.
• A packet can carry single frame from the transmission protocol.
Structure of a packet:
Packet Header
Protocol ID
Frame Length
Frame
Packet CRC
0xA5 0x1C 0x45 0xXX … 0xZZ 0xAA 0xBB
Packet
CRC protected
Figure 32: Target Status Protocol - Packet Description
Field
Length in bytes
Content
Packet Header
1
First byte of the packet.
Packet always begins with packet header.
Always equal to: 0xA5.
Protocol ID
1
Protocol identifier.
Always equal to: 0x1C
Frame Length
1
Frame field length in bytes.
Permitted value: 0x00..0xFF
Frame
up to 70
Frame contents.
Permitted value for each byte: 0x00..0xFF
Packet CRC
2
Cyclic Redundancy Check (CRC) see "Packet
CRC Definition" page 80.
The packet CRC is transmitted with MSB first.
It is used for packet integrity protection.
Permitted value for each byte: 0x00..0xFF
Table 2: Target Status Protocol - Packet Description