Watlow LogicPro - Manual (Page 142)

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
ET
Q
Timer Off Delay (TOF) Timing