System information

Section 1. Introduction
1-3
To ensure that a SerSyncByte doesn’t appear inadvertently within the message
data, it must be recognized and quoted within the body of the packet before the
packet is transmitted. The quoting process is accomplished by replacing
reserved bytes with a special code called the QuoteByte. Both SerSyncBytes
and QuoteBytes must be found in the packet body and replaced with the
following sequence:
SerSyncByte (0xbd) becomes (0xbc 0xdd)
Quote Byte (0xbc) becomes (0xbc 0xdc)
Remember that when receiving a packet, the quoted two-byte codes must be
recognized and replaced within the message body by its corresponding value in
order to interpret the data correctly.
1.3 PakBus Packet Headers
Along with a SerSyncByte, each packet must contain a PakBus header with the
appropriate information to complete the transaction. The header will contain
the following:
PakBus Header Information:
Name Type Description
LinkState bits 7..4 The state of the link described binaurally:
1000: off-line
1001: ring
1010: ready
1011: finished
1100: pause
DstPhyAddr 12 bits Address where this packet is going (MSB first)
ExpMoreCode bits 7..6 Describes whether the client should expect
another packet from this transaction.
0x00: This is the last message to this
destination from this source
0x01: Expect more messages to this destination
from the same source
0x02: Neutral message that has no impact on
whether to expect more
0x03: Expect more messages in the reverse
direction
Priority bits 5..4 The message priority on the network. Ranges
from the lowest priority, 00, to the highest
priority, 03. Priority 01 will be sufficient for
normal communication.
SrcPhyAddr 12 bits Address of the node that sent the packet (MSB
first)
HiProtoCode bits 7..4 Designates the type of higher level protocol
that will be contained in this packet:
0x00: PakCtrl Message
0x01: BMP5 Message
DstNodeId 12 bits Node ID of the message destination (MSB
first)
HopCnt bits 7..4 Always zero when connected directly
SrcNodeId 12 bits Node Id of the message source (MSB first)