Glossary – Rockwell Automation 1440-REX00-04RD XM-441 Expansion Relay Module User Manual

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Rockwell Automation Publication GMSI10-UM019C-EN-P - June 2011

Glossary

alarm

An alarm alerts you to a change in a measurement. For example, an alarm can
notify you when the measured vibration level for a machine exceeds a
pre-defined value.

Automatic Device Replacement (ADR)

A means for replacing a malfunctioning device with a new unit, and having the
device configuration data set automatically. The ADR scanner uploads and
stores a device’s configuration. Upon replacing a malfunctioning device with a
new unit (MAC ID 63), the ADR scanner automatically downloads the
configuration data and sets the MAC ID (node address).

baud rate

The baud rate is 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:

The XM measurement modules’ baud rate is automatically set by the bus
master. You must set the XM-440 Relay module baud rate. You set the
XM-440 Relay Master to 125kb, 250kb, 500kb, or Autobaud if another device
on the network has set the baud rate.

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 baud rate mismatch.

Change of State (COS)

DeviceNet communications method in which the XM module sends data
based on detection of any changed value within the input data (alarm or relay
status).

Maximum Cable Length

Cable 125K

250K

500K

Thick Trunk Line

500m (1,640ft.)

250m (820ft.)

100m (328ft.)

Thin Trunk Line

100m (328ft.)

Maximum Drop Length

6m (20ft.)

Cumulative Drop Length

156m (512ft.)

78m (256ft.)

39m (128ft.)