Specify Whether the SCADAPack x70 Device is to Detect if an Analog has Stopped Changing

The SCADAPack x70 tab on the Forms of SCADAPack x70 Analog Configuration items contains a No Change section. Use the section to specify whether the SCADAPack x70 device is to detect whether an analog's value that is expected to change is remaining static. When enabled to do so, the device compares the current engineering value of the analog with its value at the start of the calculation period and calculates the change percentage. It performs the calculation whenever the analog's current engineering value changes.

The properties in this section only apply if the analog is associated with a T_SPx70_ADV_ANALOG SCADAPack x70 logic variable (see Specify any SCADAPack x70 Logic Requirements).

• Expected Change—Use to specify the percentage of the analog's full scale, in engineering units, by which the value is expected to have changed during the specified time Period.

  (You specify the analog's full scale using the Minimum Engineering value and Maximum Engineering value in the 'Scaling' section of the tab.)

  If the analog's engineering value has not changed by at least this percentage of its full scale within the defined Period, the No Change quality is set in the T_SPx70_ADV_ANALOG SCADAPack x70 logic variable that is associated with the analog.

  Enter the required percentage, from 0 to 100 inclusive. The default is 0, which disables the feature.

• Period—Use to specify the period of time (in seconds) over which the SCADAPack x70 device should calculate whether the analog's value is deemed to have not changed. Enter the required interval in the OPC Time Format. You can enter the value directly in the field, or use the Interval window (accessed via the field's browse button) to specify the required value.

  The default of 0 disables the Rate of Change feature.