System information

Section 1. Introduction
1-2
1.2 Packet Structure
The first and last bytes are 0xbd to mark the beginning and end of a packet
Link State 4 bits
Destination physical address 12 bits MSB firs
t
Expect more code 2 bits
Priority 2 bits
Source physical address 12 bits MSB firs
t
Hi proto code 4 bits
Destination node ID 12 bits MSB first
Hop count 4 bits
Source node ID 12 bits MSB first
Message type 1 byte
Transaction ID 1 byte
Message Body
Signature Nullifier
Header (8 bytes)
Message (0...998 bytes)
1 byte
1 byte2 bytes
1.2.1 PakBus Packet Framing and Quote Bytes
PakBus data packets always end with a reserved or special byte code called a
SerSyncByte (0xbd
1
) used to identify and isolate each complete packet. Also,
one or more SerSyncBytes are transmitted before a data packet. Sending extra
SerSyncBytes through an RS-232 interface will clear residual characters from
the receiving node’s input buffer or wake the node up in preparation for
communication.
1
The character string (0xbd) designates that the characters “bd” are actually
hexadecimal representations of the values within the transmission. The
character sequence “0x” is a common hexadecimal prefix notation and is used
throughout this document when referring to hexadecimal values. Please note
that when viewing included log files, the characters “bd” will appear without
the “0x” prefix. For reference, the hexadecimal value “b” correlates to the
decimal value “11” or the binary value of “1011” while the hexadecimal value
“d” correlates to the decimal value “13” or the binary value of “1101”.