Configure PAO instructions

Use the
Advanced
 tab of the
PAO Properties
 dialog box to configure the Process Analog Output (PAO) instructions to:
  • Specify what the selected (PAO) instruction/function block should do with the CV output value in interlock and I/O fault.
  • Enter scaling limits for converting values in raw units provided by the device feedback into engineering units and scaling limits applied when converting CV output values in engineering units to raw units used by the commanded device.
To configure a Process Analog Output (PAO) instruction
  1. On the instruction in the routine, perform one of these actions:
    • On the Ladder or FBD instruction, select .
    • In the Structured Text editor, right-click the tag name and select
      Configure <tag name>
      .
  2. Select the
    Advanced
     tab.
  3. Set the parameters.
    • When interlock is not OK or I/O fault
      .
      • Hold last good CV value.
         Select to configure the instruction on interlock or on I/O fault. Select this option to use the last good CV value instead of the input CV value provided by Operator/Program/External/Override.
      • Use interlock CV target value
        . Select to configure the instruction on interlock or on I/O fault. Select this option to use the interlock CV target value instead of the input CV value provided by Operator/Program/External/Override.
    • Shed on device fault.
       Select to enable shedding the device on device fault.
    • Shed on I/O fault.
       Select to enable shedding the device on I/O fault.
    • Bumpless program/operator transition
      . Select to set up bumpless behavior of setting parameters when switching instruction owners. When the owner is Program, the operator settings track the program settings. When the owner is Operator the program settings track the operator settings and the virtual inputs match the output values (transitions are bumpless).
    • Bumpless transition from override/hand to program/operator
      . Select the check the check box to set up bumpless behavior of setting parameters when switching instruction owners. When the owner is Override, the operator and program settings track the override settings. When the owner is Hand, the operator and program settings track the hand settings (transitions are bumpless).
    • Skip rate-of-change limiting in interlock trip, maintenance and override modes
      . Rate-of-change limiting is not applicable in Out-of-service and Hand. Select to bypass CV rate-of-change limiting also in Interlock trip, Maintenance and Override.
    • Device provides pulse output.
       PAO instruction is configured for device providing pulse output (device Open, device Close). Ratchet valve is a typical device for this mode of operation.
    • Device “active” when scaled CV out is greater than
      . Type the value (engineering units) to specify when the output CV is considered to be moved. When the output CV is greater than this value, the instruction sets the status Sts_Active. When the output CV is smaller than this value the status Sts_Active is cleared. Sts_Active is typically used in HMI.
    • Output scaling limits.
      • Engineering units
        . Maximum and minimum values (engineering/CV units) used in output CV scaling.
      • Raw units
        . Output (unscaled) maximum and minimum for scaling in raw units. Raw units must be set to the range of the signal connected to the raw CV output. The output is then scaled to the values set by the Min and Max raw (CV) unit values.
    • Power up CV
      .
      • Use power up CV
        . Select to use the initial CV value on power up.
        • CV initial value used on power up
          . Enter the initial CV value (engineering units) used on power up when the device is configured to use the power up CV.
      • Use last (power down) CV
        . Select to use the last CV (from last power down) on power up.
      • Use position feedback
        . Select to use the position feedback as the CV value on power up.
  4. View the read-only parameters:
    • Device state
      . When the
      Logix Designer
       application is online with the controller, the indicator displays the current device state, such as Off, Pulse on, or Out of service.
    • Device issues.
       When the
      Logix Designer
       application is online with the controller, the indicator displays fault conditions, such as Feedback fault or I/O fault.
  5. Select
    Apply
    .
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