Scan Rates

The Plant SCADA OPC 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, tags are scanned at the default scan rate defined by the ScanRate parameter in the project Citect.INI file. See Citect.INI specific parameters for details.

Examples

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

  [OPC]
  ScanRate=1000

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

  [OPC]
  ScanRate=1000

• 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