Campbell NL200, Instruction Manual

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A-1
Appendix A. Glossary
Beacon Interval
Devices in a PakBus® network may broadcast a hello-message to other
devices in order to determine “neighbor” devices. Neighbor devices are
devices that can be communicated with directly by the current device
without being routed through an intermediate device. A beacon in a
PakBus network helps to ensure that all devices in the network are aware
of which other devices are viable in the network.
Bridge (Bridging, Network Bridge)
In the context of this manual, bridging is the act of connecting two
network interfaces at the data link layer. The NL200/201 acts as a semi-
transparent bridge passing, without alteration, IP packets between the
Ethernet and CS I/O ports.
DHCP (Dynamic Host Configuration Protocol)
A TCP/IP application protocol in which IP addresses are assigned
automatically by a DHCP server. Note that an IP address obtained
through DHCP is not static but is leased for a period of time set by the
network administrator. The address may change, if the NL200/201 is
powered down.
Hello Exchange
A communication exchange that establishes two PakBus® devices as
neighbors. A hello command packet is sent by one PakBus device (A) to
another device (B). Device (B) then sends a hello response (A). The
receipt of that packet establishes the two devices as neighbors. Only a
hello exchange can establish two devices as neighbors.
Neighbor (PakBus® Neighbor)
A device in a PakBus network that can be communicated with directly
(i.e., not via a router). Every PakBus device maintains its own Neighbor
List.
PakBus®
Campbell Scientific’s packet-switched communications protocol. Packets
of information transmitted between PakBus devices contain user data and
administrative information (a header) that routing devices use to move the
packets to their ultimate destination. PakBus devices examine the header
information and then either remove the header (at the packet’s final
destination) or forward the packet to another PakBus device.
PakBus® Node
A device in a PakBus network. Each device in a network must have a
unique PakBus address.