Rockwell Automation 1747-SDN SLC 500 DeviceNet Scanner Module User Manual - Manual (Page 114)

Publication 1747-UM655B-EN-P - June 2007
114 AutoScan
When a scanner is transitioned from Run mode to Idle mode while
AutoScan is enabled, it only scans the network for nodes that are not
already in the scanlist. However, while in Idle mode, an AutoScan
Disable mode to Enable mode transition will cause the scanner to
erase the existing scanlist and scan for all nodes on the network.
The AutoScan feature enables Auto-address Recovery (AAR) for each
of the configured slave devices.
The AutoScan feature checks for the Quick Connect setting in each
slave device and enables Quick Connect in the scanner if it is enabled
in the slave devices.
Additionally, AutoScan changes the default setting of InterScan Delay
(ISD) from 10 ms to 4 ms. The reason for this is to improve network
performance. The smaller value of ISD limits the access that software
has for communication on the network, but when using AutoScan
software communication should not be a concern.