Campbell Scientific CR6 CR6 Measurement and Control System - Page 399

PakBus Troubleshooting

Page 399 highlights

Section 8. Operation • If Beacon Interval = 0 and Verify Interval = 0, then CVI = 300 seconds* • If the router or master does not hear from a neighbor for one CVI, it begins again to send a hello-message to that node at the random interval. Users should base the Verify Interval setting on the timing of normal communications such as scheduled LoggerNet-data collections or datalogger-todatalogger communications. The idea is to not allow the CVI to expire before normal communications. If the CVI expires, the devices will initiate helloexchanges in an attempt to regain neighbor status, which will increase traffic on the network. 8.5.4 PakBus Troubleshooting Various tools and methods have been developed to assist in troubleshooting PakBus networks. 8.5.4.1 Link Integrity With beaconing or neighbor-filter discovery, links are established and verified using relatively small data packets (hello-messages). When links are used for regular telecommunications, however, longer messages are used. Consequently, a link may be reliable enough for discovery using hello-messages but unreliable with the longer messages or packets. This condition is most common in radio networks, particularly when maximum packet size is >200. PakBus® communications over marginal links can often be improved by reducing the size of the PakBus® packets with the Max Packet Size setting in DevConfig Advanced tab. Best results are obtained when the maximum packet sizes in both nodes are reduced. 8.5.4.1.1 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 CR6 sends. Note PakBus® uses the file-receive transaction 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 CR6 sends is governed by the Max Packet Size setting for the datalogger as well as that of any of its parents in the LoggerNet 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. The CR6 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. 399

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Section 8.
Operation
If
Beacon Interval
=
0
and
Verify Interval
=
0
, then CVI = 300 seconds*
If the router or master does not hear from a neighbor for one CVI, it begins
again to send a hello-message to that node at the random interval.
Users should base the
Verify Interval
setting on the timing of normal
communications such as scheduled
LoggerNet
-data collections or datalogger-to-
datalogger communications. The idea is to not allow the CVI to expire before
normal communications. If the CVI expires, the devices will initiate hello-
exchanges in an attempt to regain neighbor status, which will increase traffic on
the network.
8.5.4
PakBus Troubleshooting
Various tools and methods have been developed to assist in troubleshooting
PakBus networks.
8.5.4.1 Link Integrity
With beaconing or neighbor-filter discovery, links are established and verified
using relatively small data packets (hello-messages). When links are used for
regular telecommunications, however, longer messages are used. Consequently, a
link may be reliable enough for discovery using hello-messages but unreliable
with the longer messages or packets. This condition is most common in radio
networks, particularly when maximum packet size is >200.
PakBus
®
communications over marginal links can often be improved by reducing
the size of the PakBus
®
packets with the
Max Packet Size
setting in
DevConfig
Advanced
tab.
Best results are obtained when the maximum packet sizes in both
nodes are reduced.
8.5.4.1.1 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 CR6 sends.
Note
PakBus
®
uses the file-receive transaction 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 CR6 sends
is governed by the
Max Packet Size
setting for the datalogger as well as that of
any of its parents in the
LoggerNet
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. The CR6 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.
399