Use the Retrieval Intervals section of the '<Driver Type>' tab to determine how often the driver polls a Modbus controller to retrieve its point data:
- Normal 1 to Normal 8—Specify the frequency with which the driver polls the controller for point data. You can specify up to eight different polling intervals.
Enter each interval in the OPC Time Format, for example 10S for ten seconds.
- Promoted 1 to Promoted 8—Specify the frequency with which the driver polls the controller for point data when scanning is promoted. You can specify up to eight different polling intervals. Each Promoted frequency replaces the corresponding Normal frequency while scanning is promoted for the controller. For more information, see Temporarily Increasing the Scan Rate, and see Define Whether an Outstation is Promoted While its Points are on Display.
Enter each interval in the OPC Time Format, for example 5S for five seconds.
To define which of the eight Normal/Promoted intervals is used for a particular point, use the Retrieval Interval field on the <Point> tab of the corresponding Advanced Modbus Point Form (see Configure Common Point Properties).
Example:
An Analog point on a Generic Modbus controller has this configuration:
Retrieval Interval:5
The Generic Modbus Controller includes this configuration:
Normal Retrieval Interval 5:8S
Promoted Retrieval Interval 5:4S
The Promote when Displaying Points check box is selected.
Geo SCADA Expert scans the Generic Modbus controller every eight seconds for the Analog point data.
A Mimic that contains a point from the Generic Modbus controller is displayed on one of the ViewX workstations.
While the Mimic is on display, scanning of the controller is promoted. While scanning is promoted, Geo SCADA Expert scans the Generic Modbus controller at four-second intervals for the Analog point data.
For further information on retrieval intervals, see Normal and Promoted Scanning.