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Section 14. PakBus Overview

14.4.6 Maintaining Links

Links are maintained by means of the CVI (communications verification

interval). The CVI can be specified in each node with DevConfig. The following

rules

apply:

• If Verify Interval = 0, then CVI = 2.5 x beacon interval*

• If Verify Interval = 60, then CVI = 60 seconds*

• If Beacon Interval = 0 and Verify Interval = 0, then CVI = 300 seconds*

• If a 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 verification intervals on the timing of normal

communications such as scheduled LoggerNet collections or datalogger to

dataloggers communications. The idea is to not allow the verification interval to

expire before normal communications. If the verification interval expires the

devices will initiate hello exchanges in an attempt to regain neighbor status,

increasing traffic in the network.

Note: During the hello-message, a CVI must be negotiated between two

neighbors. The negotiated CVI is the lesser of the first nodes CVI and 6/5ths of

the neighbors CVI.

14.5 Troubleshooting

Various tools and methods have been developed to assist in troubleshooting

PakBus® networks.

14.5.1 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 but unreliable with larger packets.

This condition is most common in radio networks, particularly when max packet

size is >200.

PakBus® communications over marginal links can often be improved by

reducing the size of the PakBus® packets. Best results are obtained when the

maximum packet sizes in both nodes are reduced.

During the hello-message, a CVI must be negotiated between two neighbors.

The negotiated CVI is the lesser of the first nodes CVI and 6/5ths of the

neighbors CVI.

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Campbell CR200 Manual del operador Pagina 150