Campbell Scientific CR800 and CR850 Measurement and Control Systems - Manual (Page 337)

Section 8. Operation
337
Table 80. PakBus Leaf-Node and Router Device Configuration
Network
Device
Description
PakBus
Leaf Node
PakBus
Router
PakBus
Aware
Transparent
SC932A Serial interface •
COM220
Telephone
modem
•
COM310
Telephone
modem
•
SRM-5A
Short-haul
modem
•
1
This network link is not compatible with CR800 datalogger.
8.5.3 Linking PakBus Nodes: Neighbor Discovery
New terms (see Nodes: Leaf Nodes and Routers
(p. 335)
):
• node
• link
• neighbor
• neighbor-filters
• hello
• hello-exchange
• hello-message
• hello-request
• CVI
• beacon
To form a network, nodes must establish links with neighbors (neighbors are
adjacent nodes). Links are established through a process called discovery.
Discovery occurs when nodes exchange hellos. A hello-exchange occurs during a
hello-message between two nodes.
8.5.3.1 Hello-message (two-way exchange)
A hello-message is an interchange between two nodes that negotiates a neighbor
link. A hello-message is sent out in response to one or both of either a beacon or a
hello-request.
8.5.3.2 Beacon (one-way broadcast)
A beacon is a broadcast sent by a node at a specified interval telling all nodes
within hearing that a hello-message can be sent. If a node wishes to establish itself
as a neighbor to the beaconing node, it will then send a hello-message to the
beaconing node. Nodes already established as neighbors will not respond to a
beacon.