Methods of retrieving data from AVEVA Enterprise SCADA

Note: For information on overriding default configuration settings, refer to Modify configuration settings.

The PI-OASyS Interface uses three methods to retrieve information from AVEVA Enterprise SCADA.

Note: Data can be archived in the PI system provided that the data has the correct data type. In the event that a field is a slot number, you will need to define a state table in the PI system so that the latter recognizes the number and returns the correct value.

To scan points at fixed frequencies

The scan frequencies are defined in the PIOASYS.json file as the parameter passed to piuniint.exe in PI.run_processes.csc:

{

"PIOASYS": {

"ScanFreq1": 1,

"ScanFreq2": 10,

"ScanFreq3": "00:01:00",

}

}

You can define as many frequencies as you need. Generally, points are grouped on some logical basis and an entire group of points is scanned at the same frequency. The data is sent to PI only if the value exceeds a user-defined exception specification. For digital (status) points, any change is considered an exception.

To create a PI Tag that retrieves data from RealTime database (RTDB) at a fixed frequency, set the tag attributes as per the steps below.

1. In the PI Server node, open the PI System Management Tools.

2. Select Points > Point Builder in the System Management Plug-Ins window.

   The Point Build window appears.

   

3. Do one of the following:

   • Select the New icon to create a new point.

   • Select the Search icon to search for a point.

4. Select the PI tag row you want to edit.

5. Select the Classic tab.

6. Set the following tag attributes:

   • Location2 indicates the RTDB data type.

   • Location4 indicates the scan class.

Data collection methods supported by the PI-OASyS Interface

Retrieve data based on an event point

The PI-OASyS interface also retrieves a list of data based upon exceptions on an event point. The event point has a flexible definition, but generally it is a point residing in the RTDB that the PI-OASyS interface scans at regular intervals. If the event point experiences an exception (either through manual input or through automatic update), it triggers a read of all points that have registered themselves for notification on this event.

Retrieve an unsolicited point using the PubSub Engine

When you configure a PI Tag as an input point using the PubSub Engine (PSEngine), the point value will be updated by subscribing to the configured field value of a RTDB point. The benefit of using the PSEngine over the scan class is that information is only received when the values change. For example, whenever the value of the point changes in the RTDB, PubSub will publish the new value, and the PI-OASyS interface gets the new value and sends it to the PI Server. If there is no change in the value of the point, then PubSub does not publish and the PI-OASyS interface does not receive any information.

Attributes for a PI Tag to retrieve data using PubSub