Campbell Scientific PakBus Networking Guide - Manual (Page 8)

PakBus Networking Guide
The first and last bytes are hexidecimal “bd” characters to mark the beginning and end of a packet
Link state 4 bits
Destination physical address 12 bits MSB first
Expect more code 2 bits
Priority 2 bits
Source physical address 12 bits MSB first
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...988 bytes) 1 byte 1 byte 2 bytes
FIGURE 3-1. Example PakBus Protocol Packet
Each packet also contains an error checking signature nullifier used to
acknowledge the validity of the packet.
Once the packet has been validated, the device receiving the packet reads the
message based on the structure described by the packet type declaration and, if
necessary, returns an appropriate packet to the sending device.
3.2 Device Addresses
Since each PakBus protocol packet contains a source address and a destination
address, all PakBus devices on a network must have a unique PakBus address.
PakBus addresses within 1 and 4094 are valid. However, by convention,
addresses 1 through 3999 are typically used for dataloggers and other hardware
devices on the network while PakBus addresses 4000 through 4094 are
typically used for software such as LoggerNet, PC400 or PC200W.
Although addresses 1-4094 can technically be used for any PakBus capable
device or software product on the network, an address filtering method called
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