Rockwell Automation DeviceNet Communications Module - Manual (Page 136)

Glossary-2 DeviceNet Communications Module
DeviceNet network - A DeviceNet 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
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 http://www.odva.org.
DSI: see MDI.
Electronic Data Sheet (EDS) files - Simple text files that are used
by network configuration tools such as RSNetWorx for DeviceNet to
describe products so that you can easily commission them on a
network. EDS files describe a product device type, revision, and
configurable parameters.
Explicit Messaging - Used to configure, monitor, and diagnose
devices over the DeviceNet network.
fault action - Determines how the module and connected product
act when a communications fault occurs (for example, a cable is
disconnected) or when the scanner is switched out of run mode.
The former uses a communications fault action, and the latter uses
an idle fault action.
fault configuration - When communications are disrupted (for
example, a cable is disconnected), the module and MD65 drive can
respond with a user-defined fault configuration. The user sets the
data that is sent to the drive in the fault configuration parameters
(parameters 10 (Flt Cfg Logic) and 11 (Flt Cfg Ref)). When a fault
action parameter is set to use the fault configuration and a fault
occurs, the data from these parameters is sent as the Command
Logic and/or Reference.
Maximum Cable Length
Cable 125 K 250 K 500 K
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)