The actual block mode of the PID block goes to Man if the PV status is Bad. Through the use of STATUS_OPTS, you can determine what conditions will cause the PV status to be BAD.
When the PID is configured to directly access an input channel for its input, the status of the channel input is determined as described for the Analog Input block. Otherwise, the IN parameter status is used as the block input status.
Processing of the input status within the PID block to determine the PV status may be modified by your choice of the Status options (STATUS_OPTS). The options are:
Note that the options available in a fieldbus block are different:
You can set the status options in Out of Service mode only.
If the input status is limited, the PV status is set to Bad or Uncertain when you select the Bad if Limited or Uncertain if Limited options respectively. Similarly, if the status of the input is Uncertain, then the PV status is set to Good or Bad based on your selection of enabled or disabled for the Use Uncertain as Good option.
When the Uncertain if Limited option is selected, then as long as the input status is limited, the PV status will be set to Uncertain (even when the input status is Bad). Selecting this option and the Use Uncertain as Good option disables the mode from changing to Man under these condition when the target mode is Auto.
If you select the Target to Manual if Bad IN status option and the PV status evaluates to Bad during operation, the target mode and the actual mode are set to Man. If the status of the PV changes back to Good, the target mode (and actual mode) remain in Man.