Campbell CR800 Especificações descarregar pdf (Página 302)

Section 14. PakBus Networking

14-18

14.3.8 Leaf-Nodes

A leaf-node is a PakBus device that doesn’t route packets, although it might be

capable of it if so configured. The routing table for a leaf-node is limited to its

neighbor list. PakBus Graph, Show Settings will only display the links to a

leaf node’s neighbors.

If a message is initiated by the CR800 (using SendVariables(), GetVariables(),

SendGetVariables(), SendData(), SendTableDef(), or ClockReport()), and the

parameter for the neighbor address is set to −1, meaning “discover the route”,

a leaf-node will route through the first router neighbor it finds in its discovered

list of neighbors.

Being a router requires more resources than being a leaf node. Allow as many

nodes as possible to be leaf-nodes and allow only routers to beacon. This

prevents unnecessary links being set up between leaf-nodes which have no

purpose communicating with each other.

In a network that discovers neighbors by neighbor filter helloing, the leaf

nodes need no neighbor filter as they will be discovered by their respective

routers.

Where LoggerNet is not beaconing and communicates with a leaf node directly

(for example, by RS-232 or via RF401s), the communication verification

interval will be infinite. Once established, LoggerNet will keep the leaf node

as a neighbor forever (or until its neighbor list is reset, which occurs with a

PakBus Graph Reset Node or when LoggerNet is closed).

14.3.9 Beacons and Neighbor Filters

Beaconing is a convenient way for PakBus devices to discover neighbors;

however, beaconing can result in the routing system selecting a direct but

unreliable RF link over a better path with router. For RF4xx networks with

routers, some beaconing may need to be turned off and neighbor filters

employed. Use PakBus Graph Ping Node to verify links (see 14.2.3).

Creating a CR800 neighbor filter is a two-step procedure. You input the

PakBus Address(es) of the Allowed Neighbors and you assign a time (in

seconds) for Verify Interval xxx. A PakBus device with neighbor filter will

send hello packets in an attempt to establish as neighbors the PakBus device(s)

on the allowed neighbors list. Later, if an established neighbor is not heard

from within the specified verification interval, the neighbor filter will send

hello messages to the allowed neighbor(s) to try and get a response restoring

neighbor status. Normal communications within the verification interval

prevent hellos which would otherwise consume some network bandwidth.

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Campbell CR800 Especificações Página 302