Rockwell Automation 20-750-DNET PowerFlex DeviceNet Option Module User Manual
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Rockwell Automation Publication 750COM-UM002B-EN-P - October 2012
Glossary
Controller
A controller, also called programmable logic controller, is a solid-state control
system that has a user-programmable memory for storage of instructions to
implement specific functions such as I/O control, logic, timing, counting, report
generation, communication, arithmetic, and data file manipulation. A controller
consists of a central processor, input/output interface, and memory. See also
Scanner.
Cyclic I/O Data Exchange
A device configured for Cyclic I/O data exchange transmits data at a user-
configured interval. This type of exchange ensures that data is updated at an
appropriate rate for the application and allows data to be sampled at precise
intervals for better determinism.
Data Rate
The speed at which data is transferred on the DeviceNet network. The available
data rates depend on the type of cable and total cable length used on the network.
Each device on a DeviceNet network must be set for the same data rate. You can
set the DeviceNet option module to 125 Kbps, 250 Kbps or 500 Kbps. Or you
can set it to Autobaud if another device on the network has set the data rate.
Datalinks
A Datalink is a type of pointer used by PowerFlex 750-Series drives to transfer
data to and from the controller. Datalinks allow specified parameter values to be
accessed or changed without using explicit messages. When active, each 32-bit
Datalink in a PowerFlex 750-Series drive consumes 4 bytes in the input image
table and/or 4 bytes in the output image table of the controller.
DeviceNet Network
An open producer/consumer Controller Area Network (CAN) which connects
devices (for example, controllers, drives, and motor starters). Both I/O and
explicit messages can be transmitted over the network. A DeviceNet 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 DeviceNet and the DeviceNet specification are
maintained by the Open DeviceNet Vendor’s Association (ODVA). ODVA is
online at
.
Cable
Maximum Cable Length
125 Kbps
250 Kbps
500 Kbps
Thick Trunk Line
500 m (1,640 ft)
250 m (820 ft)
100 m (328 ft)
Thin Trunk Line
100 m (328 ft)
100 m (328 ft)
100 m (328 ft)
Maximum Drop Length
6 m (20 ft)
6 m (20 ft)
6 m (20 ft)
Cumulative Drop Length
156 m (512 ft)
78 m (256 ft)
39 m (128 ft)