Campbell RF410 Manual de Instruções descarregar pdf (Página 64)

PakBus Networking Guide

Example 2 – LoggerNet (ffe) is beaconing and CR205 (003) is nearby:

LoggerNet broadcast beacon:

15:37:21.665 T bd bd bd bd bd bd bd 8f ff

8f fe 0f ff 0f fe e6 60 bd

CR205 responds with hello request (0e) message:

15:37:21.800 R bd af fe 00 03 0f fe 00 03 0e e6 60 bd

LoggerNet sends CR205 hello (09) message:

15:37:22.133 T bd a0 03 7f fe 00 03 0f fe 09 2a 01 03 00 1e f1 5b bd

CR205 sends hello response (89) to LoggerNet:

15:37:22.368 R bd af fe 00 03 0f fe 00 03 89 2a 00 01 00 1e ff 2b bd

7.4.6 Hop Metric

The Hop Metric is intended to be an estimate of the worst case time required to

complete a simple transaction. It should include the time it would take to: dial,

send a short command, and receive a full length response. It is used by the

routing protocol to get an idea of link performance. It is also used to determine

network latency between routers for distributing routing information.

During a hello exchange (transaction) both nodes will advertise a Hop Metric

that they estimate to be valid for the link. After the exchange both neighbors

know how long the other neighbor estimates a worst case exchange to take. The

longer estimate of the two is passed on to the routing protocol as the Hop

Metric for the link.

Hop metrics determine response time, which is the time that it takes to move a

packet from one node to another.

Hop Metrics are necessary to executing the ‘shortest path routing algorithm’

that every PakBus router uses to choose the shortest (fastest) route to a

destination node.

Hop metrics (in seconds) can be viewed in a datalogger’s *D17 Routing Table.

7.4.7 Goodbye Message

When a device’s PakBus Address is changed (via *D15 or sending a program

with PakBus Settings), a goodbye-message using the old address is broadcast

out all ports which have a neighbor. This allows the network to update viable

links.

Example Goodbye message:

bd 8f ff 90 01

0f ff 00 01 0d 00 18 37 bd

PakBus device address 001 is broadcasting (to xf ff) the good-bye (od)

message.

With an “Is Dialed” setup, LoggerNet sends a Goodbye Command to the device

before disconnecting so the device will know not to hello LoggerNet.

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Campbell RF410 Manual de Instruções Página 64