Watlow LogicPro - Manual (Page 165)

LogicPro User’s Guide Chapter 10: Function Blocks
Doc.# 28002-00 Rev 3.00 Watlow Anafaze 149
Figure 10.29 Real Add Function Block
Inputs
EN is the Real Add enable bit. A True condition of this bit
causes the value of RA to be added to the value of RB and the
result stored in RC. 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 EN is 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.
RA is one value to be added. 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 value to be added. 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.
Outputs
ENO is the Real Add output bit. This bit is enabled and passes
power when the enable bit EN is True and the value of RC does
not go out of range.
RC is the Real Add result value. RC contains the sum of RA
and RB, as long as the enable bit is True. The range of values
this Variable can assume is from -3.4x10
38 to 3.4x10 38 . This
Variable retains its previous value if EN is not True. Likewise,
if the value of RC falls outside this range, ENO is disabled. RC
reverts to its last valid value whenever ENO is disabled.
Real Subtract (RSUB)
The Real Subtract (RSUB) function block, shown in Figure
10.30 on page 150, produces the difference between two
values.