Campbell Scientific CR200/CR200X-series Dataloggers - Manual (Page 149)

Section 14. PakBus Overview
14.5.1.1 Automatic Packet Size Adjustment
The BMP5 file receive transaction allows the BMP5 client (LoggerNet) to
specify the size of the next fragment of the file that the CR200(X) sends.
Note The file receive transaction is used to get table definitions from the
datalogger.
Because LoggerNet must specify a size for the next fragment of the file, it uses
whatever size restrictions that apply to the link.
Hence, the size of the responses to the file receive commands that the CR200(X)
sends is governed by the maxPacketSize setting for the datalogger as well as
that of any of its parents in LoggerNet's network map. Note that this calculation
also takes into account the error rate for devices in the link.
BMP5 data collection transaction does not provide any way for the client to
specify a cap on the size of the response message. This is the main reason why
the "Max Packet Size" setting exists in the CR200(X). The CR200(X) can look
at this setting at the point where it is forming a response message and cut short
the amount of data that it would normally send if the setting limits the message
size.
14.5.2 Ping
Link integrity can be verified with the following procedure by using
PakBusGraph | Ping Node. Nodes can be pinged with packets of 50, 100, 200 or
500 bytes.
Note Do not use packet sizes greater than 90 when pinging with 100 mW radio
modems and radio enabled dataloggers.
Pinging with ten repetitions of each packet size will characterize the link. Before
pinging, all other network traffic (scheduled data collections, clock checks, etc.)
should be temporarily disabled. Begin by pinging the first layer of links
(neighbors) from the PC, then proceed to nodes that are more than one hop
away. TABLE. PakBus Link Performance Gage (p. 137) provides a link
performance gage.
Table 18. PakBus Link Performance Gage
500 byte
Ping Sent Successes Link Status
10 10 excellent
10 9 good
10 7-8 adequate
10 <7 marginal
137