The Control Selector function block picks the high, low, or middle control signal from two or three PID function block primary outputs and places it at the Control Selector block's primary output. Three back calculation outputs are sent to upstream PID function blocks.
At the beginning of each scan period, the block calculates the actual mode according to the input status, target mode, and configured parameter settings. The block steps into the calculated actual mode or stays in the original mode.
Next, the block calculates the forward path primary output:
In Initializing Manual (IMan) mode, the primary output is unchanged. The BKCAL_SEL1, BKCAL_SEL2, and BKCAL_SEL3 parameter values are passed to the upstream function blocks.
In Manual (Man) mode, OUT can be set manually.
In Automatic (Auto) mode, the block selects SEL_1, SEL_2, or SEL_3 as the primary output based on the selection type parameter (SEL_TYPE). The output value is sent back to all the upstream blocks.
In Auto mode, when any of the connected SEL_ , SEL_2 or SEL_3 inputs have Bad status during block execution, the block transitions its actual mode to Man. When the Bad SEL_1, SEL_2 or SEL_3 input transitions back to Good status, the block resumes Auto operation.
All the output parameter status values are set to indicate the status of the block and the status of the corresponding parameter.
Output limit scaling
During download OUT_HI_LIM and OUT_LO_LIM are set to their configured values. If you have not changed these values from their defaults they are set as follows during the first execution of the block:
During runtime the limits are restricted as follows:
OUT_HI_LIM is restricted to OUT_SCALE(EU100) + 0.1 × (OUT_SCALE(EU100) - OUT_SCALE(EU0)).
OUT_LO_LIM is restricted to OUT_SCALE(EU0) - 0.1 × (OUT_SCALE(EU100) - OUT_SCALE(EU0)).
The OUT parameter is not changed as a result of changing the scale or limits. However, if OUT violates the new limits OUT is forced within the limits on the next execution of the block.
Output selection and limiting
You can limit the output by configuring the OUT_HI_LIM and OUT_LO_LIM parameters.