Polling Driver Tags

Available only in VTScada-based applications.

Polling driver tags are designed for use in telemetry applications where communication links may be costly, either in terms of time or money.

The polling driver tag provides the following features:

•    The ability to poll multiple stations or I/O devices in a pre-determined order and at a fixed time interval.

•    The ability to switch to fast-polling mode of selected sites on demand.  See Fast Scan Drawing Method (VTScada).

•    Provides a simple grouping of I/O tags on a single display.

Polling drivers should be configured to stand between a communications driver tag and the I/O tags.  Its function is to control the order and the frequency of data transfer between the I/O tags and the remote equipment via the communication driver tag.

All input and output tags associated with a polling driver will use the scan interval configured for the polling driver rather than their configured scan rate.  The exception to this is that  when data is written from an output tag, it is passed to the polling driver tag, and then on to the associated communication driver tag immediately.

Multiple polling drivers may be attached to a single communication driver tag, each with a separate poll rate which would allow, for example, some data to be polled every minute, and other data to be polled hourly.

 

The characteristics of the polling driver are described in the table below.

Polling Driver Characteristics

Tag Browser Name: Polling Driver

Database Table Name: PollDriver

Type: Driver

Tag Group Memberships: Container, Digitals, Drivers, Numeric, VTScadaDriver

Log Enabled Variables: None

Native Drawing Methods: Polling Driver Tag Drawing Methods (VTScada)

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