Scan Rates

The Plant SCADA ABCLX driver can define I/O devices with different scan rates. This provides you with the ability to better tune your system, by ordering the tag database into logical groups and defining different scan rates for each group. For example, tags that are being read frequently can be placed in a group that is scanned frequently, and tags that are read infrequently can be placed in a group that is scanned infrequently.

By default, all tags are scanned at the default scan rate defined by the ScanRate parameter in the project Citect.INI file.

Note: If you have configured I/O server redundancy in your project, it may be considered an inefficient use of network bandwidth to be continually polling devices non-critical to the currently inactive server. To help reduce unnecessary network traffic, the ABCLX driver supports the use of the InactiveScanAdjust parameter, which applies a delay factor to the scan rate of currently inactive I/O Servers.

See ABCLX Specific Parameters for details.

Examples

Set the project scan rate to 1 second (1000 milliseconds):

[ABCLX]
ScanRate=1000

Set the project scan rate to 1 second (1000 milliseconds), and the inactive server scan adjust rate to a factor of 5:

[ABCLX]
ScanRate=1000
InactiveScanAdjust=5

Set a faster (half second) scan rate for a specific port named "Port1" on the I/O server named "CLServer":

[CLServer.Port1]
ScanRate=500

Set a slower (5 second) scan rate for a specific port named "Port123" on the I/O port named "CLServer":

[CLServer.Port123]
ScanRate=5000