System information

3-1
Section 3. The CR200 Datalogger
The CR200 is low-cost, rugged, and versatile measurement device. This small datalogger
contains a CPU and both digital and analog inputs and outputs. The CR200 has a PakBus
operating system that communicates via the BMP5 message protocol. Pre-compiled
programs sent to the datalogger are written in a BASIC-like language that includes data
processing and analysis routines. These programs run on a precise execution interval and
will store measurements and data in tables.
The CR200 has a built in RS-232 port allowing a direct connection from a PC. Once the
PC has established a connection to the datalogger, the application running on the PC can
communicate directly to the datalogger. Unlike other dataloggers the CR200 does not
have security available in the operating system. Since a security code cannot be set in the
CR200, the SecurityCode field prevalent in many of the BMP5 protocol message bodies
can remain null.
3.1 Dealing with Unexpected, Asynchronous
Commands from the CR200
Communication on a packet switched network occurs asynchronously.
Therefore, an application must not expect response packets from the datalogger
in any particular order. Careful attention to each transaction number and
message type will help eliminate confusion with packets that are received by
the application. In addition, the DstPhyAddr value in the header of each
received packet should match the application’s advertised address or the packet
should be discarded.
There also may be packets and message types periodically sent across the
network that aren’t detailed in this document. This document attempts to
describe the critical message types necessary to facilitate communication. If
the application receives any packets from a datalogger that haven’t been
discussed in this documentation, the application should respond with a PakCtrl
Delivery Failure Message (Packet Type 0x81) specifying that the command is
not currently implemented or understood by the application.
3.2 Getting the Attention of the Datalogger
The application should initiate communication with the datalogger by using a
SerPkt Link-state “Ring” transaction. The datalogger will return a SerPkt
Link-state “Ready” packet to let the application know to proceed with
communication. Although the initial Ring and Ready packets should be used,
they are not required. If the PakBus address of the datalogger is known, the
application can send any appropriate message to the datalogger at anytime.
An example of a “Ring” packet from an application with a PakBus address of
4094 to a datalogger with a PakBus address of 1 to request the communication
link state is as follows:
BD 90 01 0F FE 71 D2 BD