Watlow LogicPro - Manual (Page 141)

LogicPro User’s Guide Chapter 10: Function Blocks
Doc.# 28002-00 Rev 3.00 Watlow Anafaze 125
The output bit (Q) is enabled upon a True condition of the
enable bit (INP). When there is a False condition of the enable
bit, TOF continues to enable the output bit while it increments
the integer elapsed time (ET) value in thousandths of a second
until the integer preset time (PT) value is reached. Once the
elapsed time value equals the preset time value, the output is
disabled. The elapsed time value resets and remains at zero as
long as the enable bit is False.
Figure 10.9 Timer Off-Delay Function Block
Inputs
INP is the Timer Off-Delay enable bit. A True condition of this
bit enables the output bit. A False condition of this bit triggers
the elapsed time to start incrementing in thousandths of a
second until the elapsed time equals the preset time. After this
delay, the output bit is disabled until the next True condition
of the enable bit. In a program using Ladder logic, the value
of INP is determined by the Boolean evaluation of elements
placed between the left power rail and INP in the function
block. In an FBD program, it is determined by the Variable
connected to INP. If no contacts are placed on the rung before
INP, the value of INP is always True.
PT is the Timer Off-Delay preset time. In Ladder logic, assign
this input a symbolic name or constant value in the
Assign
Function Block Symbolic Input/Output dialog box. In
FBD, assign a variable to this input in the Variable
Assignment dialog box. The range of values this Variable
can assume is from 1 to 32,767 for INT type Variables and 1
to 2,147,483,647 for LONG type Variables thousandths of a
second. If this Variable is assigned a value out of these ranges,
unpredictable results will occur.
Outputs
Q is the timer off-delay output bit. This bit is enabled and
passes power when the enable bit is True. When the enable bit
is False, it remains enabled until the elapsed time becomes
equal to the preset time.
ET is the timer off-delay elapsed time. The value of this
Variable increments in thousandths of a second when
triggered by a False condition of the enable bit until the