Watlow LogicPro - Manual (Page 162)

Chapter 10: Function Blocks LogicPro User’s Guide
146 Watlow Anafaze Doc.# 28002-00 Rev 3.00
Figure 10.26 Real Greater Than Function Block
Inputs
EN is the Real Greater Than enable bit. A True condition of
this bit causes the comparison between RA and RB to occur. 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 the function block. In FBD programs, the
value of CU is determined by the Variable connected to EN. If
no contacts are placed on the rung before EN in a Ladder
Diagrams program, the value of EN is always True. In FBD,
all inputs must be connected to a Variable.
RA is one comparison value. The range of values this Variable
can assume is from -3.4x10
38 to 3.4x10 38 . If this Variable is
assigned a value out of these ranges, unpredictable results will
occur.
RB is another comparison value. The range of values this
Variable can assume is from -3.4x10
38 to 3.4x10 38 . If this
Variable is assigned a value out of these ranges, unpredictable
results will occur.
Output
Q is the Real Greater Than output bit. This bit is enabled and
passes power when the enable bit is True and the value of RA
is greater than the value of RB.
Real Less Than (RLT)
The Real Less Than (RLT) function block, as shown in Figure
10.27 on page 147, tests if a real Variable value is less than a
reference value.
RLT tests whether one value (RA) is less than another value
(RB) when the enable bit (EN) is True. If the relationship
RAbit is disabled either when the enable bit becomes False or the
value of RA is no longer less than RB. The values of RA and RB
can be preset to a constant or assigned a symbolic name,
which allows their value to change dynamically within the
program.