GE FVP110, Руководство по обслуживанию

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IS (SIGSEL) Function Block
General
The signal selector block provides selection of up to four inputs and generates an output
based on the configured action (Figure 66). This block normally receives its inputs from AI
blocks. The block performs maximum, minimum, middle, average and
first good
signal
selection.
Figure 66 Inputs/Outputs of IS (SIGSEL) Function Block
With a combination of parameter configuration options the block can function as a rotary
position switch, or a validated priority selection based on the use of the first good parameter
and the disable_n parameter (Figure 67). As a switch, the block can receive switching
information from either the connected inputs or from an operator input. The block also
supports the concept of a middle selection. Although the normal configuration for this
feature would be with three signals, the block should generate an average of the middle two
if four signals are configured or the average of two if three are configured and a bad status
is passed to one of the inputs. Logic is provided for handling uncertain and bad signals in
conjunction with configured actions. The intended application of this block is to provide
control signal selection in the forward path only, therefore, no back calculation support is
provided. SELECTED is a second output that indicates which input has been selected by
the algorithm.