Rockwell Automation 1747-SDN SLC 500 DeviceNet Scanner Module User Manual - Manual (Page 153)

153 Publication 1747-UM655B-EN-P - June 2007
Glossary
Bridge
The module’s support of explicit message transfer.
Background Poll Ratio
Sets the frequency of poll messages to a device in relation to the
number of I/O scans. For example, if the ratio is set at 10, that device
will be polled once every 10 scans.
Change of State
A type of I/O data communication. The module can send and receive
data with slave devices that have the change of state feature. Data is
sent whenever a data change occurs. Data is updated at the rate of the
heartbeat.
Cyclic
A type of I/O data communication. The module can send and receive
data with slave devices that have the cyclic feature. Data is sent only
at a user-configurable rate.
Discrete I/O
The transfer of 1…32 words between an SLC 500 processor and the
1747-SDN module. All 32 words of input data and all 32 words of
output data are updated on each SLC program scan.
Dual Mode
The module is in Dual mode when it serves as a master to one or
more slaves and as a slave to another master simultaneously.
EDS
Electronic data sheets are vendor-supplied templates that specifies
how information is displayed as well as what is an appropriate entry
(value).
Explicit Messaging
A type of messaging used for lower priority tasks, such as
configuration and data monitoring.
Heartbeat Rate
Devices that are configured for change of state data can also send a
heartbeat signal to indicate proper operation.