Input Selector Block; Execution; Figure 16: Input Selector Block - Honeywell SLG 700 Option Manual

3.11 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

3.11.1.
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.
Selection Processing

If OP_SELECT is non-zero, the OP_SELECT value determines the selected input,
irrespective of the SELECT_TYPE selection. The value of SELECTED is the number of
the input used.
If SELECT_TYPE is 'First Good', it transfers the value of the first remaining input to the

output of the block. The value of SELECTED is the number of the input used.
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Figure 16: Input Selector Block

Input processing
FOUNDATION Fieldbus Option User's Manual Rev.5