When Sync Only is chosen as the Communications Mode, the WebAccess SCADA node will use the Scan Time to read data from the OPC Server. If Sync and Async is chosen, the SCAN time is ignored and WebAccess waits for the OPC Server to “advise” the SCADA Node of changes in the values of tags.
The Scan Time is in Milli-seconds (1/1000ths of a second). 1000ms = 1 sec.