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Chapter 10: Function Blocks LogicPro User’s Guide

156 Watlow Anafaze Doc.# 28002-00 Rev 3.00

a constant or assigned a Variable name, which allows their

value to change dynamically within the program.

Figure 10.36 Square Root Function Block

Inputs

EN is the Square Root enable bit. A True condition of this bit

causes the square root of RIN to be placed in ROUT. In a

program using Ladder logic, the value of EN is determined by

the Boolean evaluation of elements placed between the left

power rail and EN. In FBD programs, the value of EN

determined by the Variable connected to EN. If no contacts are

placed on the rung before EN in a Ladder Diagram program,

the value of EN is always True. In FBD, all inputs must be

connected to a Variable.

RIN is the Square Root input Variable. The range of values this

Variable can assume is from -3.4x10

to 3.4x10

If this

Variable is assigned a value out of this range, unpredictable

results will occur.

Outputs

Q is the Square Root output bit. This bit is enabled and passes

power when the enable bit is True. Place an output coil on the

rung between Q in the function block and the right power rail

(in a Ladder Diagram program) or connect an output Variable

to it (in a FBD program).

ROUT is the Square Root output Variable. This value is set

equal to the square root of the input Variable when the enable

bit is True. The range of values this Variable can assume is

from -3.4x10

to 3.4x10

If this Variable is assigned a value

out of this range, unpredictable results will occur. ROUT

retains its last valid value whenever EN is disabled.

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Watlow LogicPro Manuale Utente Pagina 172