Rockwell Automation 1747-SDN 1747-SDN DeviceNet Scanner Installation Instructions - Manual (Page 5)

1747-SDN DeviceNet Scanner Module 5
Publication 1747-IN058F-EN-P - December 2010
This feature has the following variations.
Poll
A poll message is a point-to-point transfer of data (0…255 bytes) sent by the scanner module
that solicits a response from a single device. The device responds with its input data
(0…255 bytes).
Strobe
A strobe message is a multicast transfer of data (64 bits in length) sent by the scanner module
that solicits a response from each strobed slave device. There is one bit for each of the
possible 64 node addresses. The devices respond with their data, which can be as much as
8 bytes.
Change of State
Change of state enables the scanner module to perform a scan:
• whenever a network data change occurs.
• at a user-configurable heartbeat rate.
Because data is only sent on an as-needed basis, this feature increases system performance by
reducing network traffic.
Cyclic I/O
Cyclic I/O allows you to instruct the scanner module to perform a scan at a specific send rate.
Because data is only sent at a periodic rate, this feature increases system performance by
reducing network traffic.
Module Mode Description
Null Contains an empty or disabled scan list (default)
Master Serves as a master to one or more slaves but is not simultaneously serving as a slave to
another master
Slave Serves as a slave to another master
Dual Serves as both a master to one or more slaves and as a slave to another master
simultaneously