3.10 Input Selector Block; Execution; Figure 10: Input Selector Block - Honeywell ST700 User Manual

3.10 Input Selector block

The Input Selector block performs maximum, minimum, middle, average and 'first good'
input selection. The Input Selector block provides selection of up to four inputs and
generates an output based on the selected type of input. The block normally receives its
inputs from AI blocks, and provides a combination of parameter configuration options. The
block functions as a rotary position switch, or a validated priority selection based on the use
of the first good parameter and the disable_n parameter. As a switch, the block receives
switching information from either the connected inputs or from an operator input. The
block supports signal status propagation.
The block is used to provide control input selection in the forward path only, and hence no
back calculation support is provided. SELECTED indicates which input has been selected
or the number of inputs selected by the algorithm. The block does not support process
alarms.

Execution

Input processing
If DISABLE_n is True, the corresponding input IN_n is discarded. If there are no inputs
left, or if there are inputs fewer than MIN_GOOD inputs, then the value of SELECTED
becomes zero.
Revision 2.0 FOUNDATION Fieldbus ST 700 Pressure Transmitter User's Guide

Figure 10: Input Selector block

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