Campbell CR800 Specifications download pdf (Page 298)

Section 14. PakBus Networking

14-14

14.3.5 Verification Intervals

The verification interval is the interval at which a PakBus device, which has an

established neighbor but hasn’t heard from it during normal communications,

tries to reestablish the device as a neighbor by attempting a hello-exchange.

The verification interval is either assigned (input by user to Verify Interval

xxx) or it is calculated by multiplying a device’s beacon interval by 2.5. For

communication verification, the lesser of the link’s two PakBus devices’

verification intervals will be used. For example, if LoggerNet is beaconing at

120 second intervals and a CR800 is beaconing at 60 second intervals, the

verification interval will be 60 × 2.5 = 150 seconds. This also applies when

two CR800s are communicating. When a leaf node is involved, it passes an

infinite comms verify interval.

When a link’s verification interval expires, both devices begin to hello the

other attempting to reestablish neighbor status.

A beaconing CR800 needs no Verify Interval xxx (it can be left 0); however, if

you wish shorter initial discovery time but a longer ongoing verification

interval, you can input into Verify Interval xxx a larger number than (beacon

interval × 2.5) and the CR800 will verify at that interval. For example, to half

the initial discovery time, input a Verify Interval SDC7 of 300 seconds but a

Beacon Interval SDC7 of 60 seconds.

The rule when assigning a number to the verify interval is to configure the

(verify interval) > (scheduled collection interval) so that normal scheduled

collection maintains neighbor status. With a CRxxxPB datalogger (which

lacks the “verify interval” setting) you configure the (beacon interval) >

(scheduled collection interval / 2.5).

When a CR800 has a neighbor filter, all beacons should be disabled (0). Its

communication verification interval is the user-input Verify Interval xxx.

14.3.6 Routers

A router is a PakBus device that has the capability to receive, process, re-

address, and transmit a packet toward its destination. A router also has the

ability to participate in the network routing system. Most PakBus devices

(except the CR2xx family) can function as routers if so configured. A

transparent communication device can receive and send packets, but, having

no PakBus address of its own and being unable to process and re-address a

packet or take part in the routing system, it is neither a PakBus device nor a

router.

Every PakBus device maintains a Neighbor List containing the PakBus

addresses of the devices it claims as neighbors. PakBus devices that are

Routers also have a Router List showing all the routers in the network and a

Links Table showing all the links in the network. Routers put this information

into a best-route algorithm to create a Routing Table listing all the nodes in the

network and the respective neighbors through which to route toward those

nodes. A router is responsible, if its own neighbor list changes, to notify the

other routers in its network or branch.

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Campbell CR800 Specifications Page 298

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