Glossary, To the – Rockwell Automation 20-COMM-K CANopen Adapter User Manual

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Glossary

Adapter

Devices such as drives, controllers, and computers usually require an
adapter to provide a communication interface between them and a network
such as CANopen. An adapter reads data on the network and transmits it to
the connected device. It also reads data in the device and transmits it to the
network.

The 20-COMM-K CANopen adapter connects PowerFlex 7-Class drives to
a CANopen network. Adapters are sometimes also called “cards,”
“embedded communication options,” “gateways,” “modules,” and
“peripherals.”

Bus Off

A bus off condition occurs when an abnormal rate of errors is detected on
the Control Area Network (CAN) bus in a device. The bus-off device cannot
receive or transmit messages on the network. This condition is often caused
by corruption of the network data signals due to noise or data rate
mismatch.

CANopen Network

A CANopen network uses a producer/consumer Controller Area Network
(CAN) to connect devices (for example, controllers, drives, and motor
starters). Both I/O and explicit messages can be transmitted over the
network. A CANopen network can support a maximum of 64 devices. Each
device is assigned a unique node address and transmits data on the network
at the same data rate.

A cable is used to connect devices on the network. It contains both the
signal and power wires. Devices can be connected to the network with drop
lines, in a daisy chain connection, or a combination of the two.

General information about CANopen and the CANopen specification are
maintained by the Open CANopen Vendor’s Association (ODVA). ODVA is
online at

http://www.odva.org

Change of State (COS) I/O Data Exchange

A device that is configured for Change of State I/O data exchange transmits
data at a specified interval if its data remains unchanged. If its data changes,
the device immediately transmits the change. This type of exchange can
reduce network traffic and save resources since unchanged data does not
need to be transmitted or processed.

COB-ID

The CANopen 11 bit structure combines a 4 bit function code with the node
address (0…127). This is called the COB-ID.

Communication Cycle Period

See Synchronization Object (Sync).