System information

2-1
Section 2. Protocols and Packet Types
Packet types from three distinct protocols are described in this document. The SerPkt
Protcol used to monitor the state of the communication link, the PakBus Control Protocol
(PakCtrl) used to facilitate PakBus network-level services, and the BMP5 Protocol used to
send application messages.
2.1 SerPkt Link-State Sub Protocol
SerPkt protocol allows the application and the datalogger to track and control
the state of their communication link on the network. The application can
request the datalogger’s state before attempting to send messages with a “ring”
packet. If the datalogger responds with a “ready” packet, the application
should be able to proceed with communication.
Some possible link-states sent by the application and a possible response from
the datalogger, depending on the state of the device, include but are not limited
to the following few examples:
Ring –> Ready
Ready with a message –> Ready with data
Finished with a message –> Ready with data
Finished –> Off-line
Pause –> Finished with or without data
The SerPkt protocol discussed in this section is the Link-state Sub Protocol. If
the developer can communicate between the application and the datalogger
with this protocol layer, all other protocols discussed in this document should
be implemented easily as additional layers working with this SerPkt protocol.
With Link-state Sub Protocol communication, a node initiates a link check and
the receiving node responds with a corresponding Link-state Sub Protocol
packet declaring the current state. Packets with four bytes of data will only
contain the state of the communications link while packets with more than four
bytes of data will contain additional link information and possibly even
message data. The format for this packet is outlined in the following table.