Campbell NL200, Руководство пользователя

Страница: 37 / 64

A-1
Appendix A. Glossary
Beacon Interval
Devices in a PakBus network may broadcast a hello-message to other devices
in order to determine “neighbour” devices. Neighbour 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
neighbours. 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 neighbours. Only a hello
exchange can establish two devices as neighbours.
Neighbour (PakBus Neighbour)
A device in a PakBus network that can be communicated with directly (i.e.,
not via a router). Every PakBus device maintains its own Neighbour 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.