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Modbus II
An industrial networking system that uses tokenĆpassing
peerĆtoĆpeer communications at data transfer rates of five megabits
per second. The network medium is coaxial cable.
modem
Modulator/demodulator. A device that conditions digital data for
transmission along an analog signal path, or conditions input
signals received from the path for use as digital data.
network
The interconnection of devices sharing a common data path and
protocol for communication. On Modbus Plus, the devices share in
the passing of a common token frame to gain sequential access for
sending messages.
Network Option Module
A hardware module that is mounted into a common backplane
together with a Programmable Controller, communicating with the
controller over the backplane. The module connects to the
Modbus Plus network and provides the central point for
communication between the controller's application program and
the node devices on the network.
node
A device that has a direct point of access to a communications
network. On Modbus Plus, any device that is physically connected
to the network.
OSI Model
Open Systems Interconnection Model. A reference standard
describing the required performance of devices for data
communication. Produced by the International Standards
Organization.
Peer Cop
A method of peerĆtoĆpeer communication between networked
devices in which data is transferred as part of the passing of tokens
between nodes. Each node passes the token in the network's
address sequence, and can be configured to transmit data in
addition to the token. All nodes monitor the token passes, and can
be configured to extract data from them. Nodes are setup for Peer
Cop transfers as part of their initial configuration, and continue
using Peer Cop as long as they are active on the network. Four
kinds of Peer Cop communication can be transacted during each
token pass: see Global Input, Global Output, Specific Input,
and Specific Output.