CONTROL LOOP DIAGRAMS
Process Controls
Figure 5 Block and Arrows
Although blocks are used to identify many types of mathematical operations, operations of
addition and subtraction are represented by a circle, called a summing point. As shown in Figure
6, a summing point may have one or several inputs. Each input has its own appropriate plus or
minus sign. A summing point has only one output and is equal to the algebraic sum of the
inputs.
Figure 6 Summing Points
A takeoff point is used to allow a signal to be used by more than one block or summing point
(Figure 7).
IC-07
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