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Chapter 10: Function Blocks LogicPro User’s Guide

126 Watlow Anafaze Doc.# 28002-00 Rev 3.00

elapsed time is equal to the preset time. The elapsed time

retains this value until the enable bit is True again. Prior to the

first initialization of this function block, the elapsed time does

not increment even though the enable bit is False.

Figure 10.10 illustrates the relationship between the inputs

and outputs of the TOF function block and shows how the INP

signal and ET (timer) determine the state of the output Q, INP

and Q signals are high or low. ET is an analog value on the

vertical axis. Time is on the horizontal axis.

Figure 10.10 Relationship Between Inputs and

Outputs of TOF Function Block

Comparison

The following section contains descriptions of comparison

function blocks found in the standard category.

Greater Than (GT)

The Greater Than (GT) function block, shown in Figure

10.11, tests if a value is greater than a reference value.

GT tests whether one value (A) is greater than another value

(B) when the enable bit (EN) is True. If the relationship A>B is

True, then the output bit (Q) is enabled. The output bit is

disabled either when the enable bit is False or the value of A is

no longer greater than B. The values of A and B can be preset

to a constant or assigned a symbolic name, which allows their

value to change dynamically within the program.

Figure 10.11 Greater Than Function Block

INP

Timer Off Delay (TOF) Timing

1 2 ... 137 138 139 140 141 142 143 144 145 146 147 ... 295 296

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