Rockwell Automation T3833 User Manual
ICS Regent
I
mportant!
®
PD-6043
Math Package for
W
INTERPRET
Floating Point Math Function Block
(T3833)
Issue 1,
The Math pac
package which allows the user to create Floating Point Math
function blocks for Regent application programs. When
installed on the PC, the math package is seamlessly
integrated with the base WINTERPRET
Floating point math function blocks are used to perform
mathematical calculations that require floating point
precision or use values that exceed the 16-bit signed integer
range (-32768 to +32767) used in ladder logic math
operations. The expressions that can be used in floating point
math function blocks include addition, subtraction, division,
multiplication, exponentiation, logarithms, and square root.
kage for W
INTERPRET
is an add-in software
software.
March, 06
Software Installation
The Math package is installed on the PC running the
W
INTERPRET
package provides the necessary installation software to install
this add-in math package. The math package should be
installed at the same time or after you have installed the
W
INTERPRET
Installation Procedure
The files on the Math package diskette are in compressed
form. You cannot simply copy the files to your hard drive —
they must be decompressed before they will run. You must
have the WINTERPRET base package distribution disk in order
to run the setup procedure to install the Math package.
To install the Math package, use the following sequence:
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1
application software. The W
base package.
INTERPRET
base
Math Package for
1. Insert the WINTERPRET base package distribution disk into
W
INTERPRET
drive A: or B:
(T3833)
2. Start Windows (if it isn’t already running).
3. Choose Run from the Program Manager’s File menu.
4. Type a:\
W
INTERPRET base package disk in drive B: type
b:\setup.exe
5. In the WINTERPRET Setup dialog box enter the name of the
directory in which you have installed the WINTERPRET
base package (This assumes that you have already
installed WINTERPRET). Choose Continue.
6. In the WINTERPRET Installation dialog box check the Math
package box.
7. Choose OK to have the setup program install the Math
package software.
When the installation is completed, you can run the
W
INTERPRET application and create floating point math
function blocks in you application programs.
setup.exe
.) Choose OK or press ENTER.
in the text box. (if you inserted the
Working with Floating Point Math Function Blocks
Floating point math function blocks are created as part of an
application program which may also contain other types of
function blocks. A single application program is made up of as
many as 50 function blocks of any type or combination.
When you installed the Math package, additional sof
was added to W
point math function blocks. With this additional software you
can create floating point math function blocks by opening a
project, opening a program and opening (or creating) a
function block.
For an overview about Regent application programs and
function blocks and how to create them using WINTERPRET
refer to Section 5, Working with Programs and Function
Blocks in the Regent User’s Guide.
INTERPRET
to allow you to work with floating
tware
,
2
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Math Package for
W
INTERPRET
(T3833)
Using Floating Point Math Statements
In floating point math function blocks you enter
mathematical equations and expressions in the form of
statements. Each line can contain one statement that
calculates the result of a mathematical equation. For
example, consider the quadratic equation below.
y = 1.6x2 +8x -22.4
Using floating point math the statement representing this
equation would be:
Y = 1.6*X^2 + 8*X - 22.4
You can also enter comments in any line by entering a
semicolon (;) and placing your comments after the semicolon
as shown below.
Y
= 1.6*X^2 + 8*X - 22.4 ; This is a comment.
Floating point math also allows you to create conditional
statements using IF, ELSE, ENDIF, WHILE, ENDW, AND
and OR operations. Below is an example of using IF, ELSE
and ENDIF to calculate the absolute value of the difference
between two variables.
PD-6043
March, 06
IF AI1 > AI2
DIFF = AI1 - AI2
ELSE
DIFF = AI2 - AI1
ENDIF
Using combinations of conditional statements and
mathematical operations allows you to configure floating
point function blocks to meet a wide range
requirements.
Mathematical Operations
of control
The mathematical operators perform arithmetic and
functional operations.
3
Math Package for
Operator Operation
^ Exponentiation
* Multiplication
/
Division
+
Addition
- Subtraction
Operator Operation
SQRT(x)
Returns the square root of x
EXP(x)
Raises e to the x power
LOG(x)
Returns the logarithm of x
LN(x)
Returns the natural logarithm of x
Note:
Note:
W
INTERPRET
(T3833)
Arithmetic Operations
Table 1 shows the arithmetic operators recognized by floating
point math listed in their default order of precedence.
Table 1. Arithmetic Operators.
Multiplication and division have equal precedence from
right, as do addition and subtraction.
The exponent, X, in an exponential expression (
Y^X
left to
) is always
evaluated as an integer (fractional portion is truncated). Do
not use the exponentiation operator to perform square root
calculations, instead use the
below.
SQRT(X)
function described
Parentheses may be used to clarify the order of operation:
operations within parenthesis are performed first. Inside the
parentheses, the usual order of precedence is maintained.
Functional Operators
A functional operator is used in an expression to perform a
predetermined operation that is to be performed on one or
more operands. The Regent’s floating point math has four
standard functions that reside in the system as shown in
Table 2.
Table 2. Functional Operators.
In each function you can enter a variable or arithmetic
expression within the parenthesis of the function. For
example the following statement is valid.
4
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Math Package for
Note:
W
INTERPRET
(T3833)
The exponentiation operator (
integer power X. If you need to calculate
values of X you can use the
shown below.
Conditional Statements
ROOT1 = (-B + SQRT(B^2 - 4*A*C)) / (2*A)
Y^X
) can only raise Y to an
YX for non-integer
LN(X)
and
EXP(X)
functions as
Y_2_THE_X = EXP(X*LN(Y))
The statements available in the floating point math let you
alter program flow base
IF, ELSE, and ENDIF
d on testing of conditions.
The IF statement is used to make a decision regarding
program flow based on the result returned by an expression.
The expression can include mathematical and logical
operators. The use of ELSE within the lines controlled by the
IF statement is optional.
Syntax:
IF expression
•
•
ELSE (optional)
•
•
ENDIF
IF, ELSE, and ENDIF statements must not
the same line.
WHILE and ENDW
be combined on
The WHILE statement executes a series of statements in a
l
oop as long as the expression is true. The expression can
include mathematical and logical operators.
Syntax:
WHILE expression
•
PD-6043
March, 06
•
loop statement
5
Math Package for
Operator
Relation Tested
Expression
=
Equality
X = Y
<> Inequality
X <> Y
<
Less than
X < Y
>
Greater than
X > Y
<= Less than or equal to
X <= Y
>= Greater than or equal to
X >= Y
Important!
If the expression is true (not zero), loop statements are
executed until the ENDW statement is encountered. Floating
point math then returns to the WHILE statement and checks
expression. If expression is still true, the process is repeated.
If the expression is not true, execution resumes with the
statement following the ENDW statement.
To avoid infinite loops, the expression must be modified (its
value changed) during repeated execution to make the
expression false and exit the loop.
W
INTERPRET
•
•
ENDW
(T3833)
WHILE and ENDW statements may be nested.
Relational and Logical Operators
Relational and logic operators are often used in the
expressions for IF and WHILE statements to control the
execution of other mathematical statements.
Relational Operators
Relational operators compare two values. The result of the
comparison is either true (1) or false (0
). The result can then
be used to make a decision regarding program flow. The
relational operators are shown in Table 3.
Table 3. Relational Operators.
6
When arithmetic and relational operators are combined in
one expression, the arithmetic is always p
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erformed first.
Math Package for
Value
A
Value
B
Result
A AND B
Result
A OR B
T T T T
T F F T
F T F T
F F F
F
W
INTERPRET
(T3833)
Logical Operators
Logical operators perform logical, or boolean, operations on
numeric values. Just as the relational operators are usually
used to make decisions regarding program flow, logical
operators are used to connect two or more relations and return
a true or false value to be used in a decision.
A logical operator takes a combination of true/false values and
returns a true or false result. An operand of a logical operator
is considered to be true if it is not equal to zero, or
false if it is
equal to zero. The result of the logical operation is a number
which is, again, true if it is not equal to zero, or false if it is
equal to zero.
In an expression, logical operations are performed after
arithmetic and relational operations.
Table 4. Logical Operators.
Using Variables and Constants
Constants
Constants are static values used by the floating point math
function blocks during execution of your program. All
constants are numeric.
Numeric constants can be either positive or negative.
Numeric constants must not contain commas. For example, if
the number 20,000 is needed as a constant, it should be typed
in the floating point math statement as 20000.
There are two types of numeric constants: integer and floating
point.
PD-6043
March, 06
7
Math Package for
W
INTERPRET
(T3833)
Integer Constants
Integer constants are constants entered as whole numbers
that do not contain decimal points or commas. Entering
an
integer constant greater than 7 numerals long is allowed but
the precision of the actual number stored and used in the
Regent is limited to 7 significant digits. For example, the
integer constants 12345678 and 12345679 may result in an
equal values when converted and stored in the Regent.
Floating Point Constants
Floating point constants are positive and negative numbers
represented in exponential form (similar to scientific
notation). A floating point constant consists of an optionally
signed integer or fixed point number (the mantissa) followed
by the letter "E" and an optionally signed integer (the
exponent). The "E" means "times ten to the power of."
For example:
33E-2
Here, 33 is the mantissa, and -2 is the exponent. This number
could be read as "thirty-three times ten to the power of
negative two." You could also write this number as 0.33 in
regular fixed point notation.
8
You can represent any number from -1.175494E-38 to
3.402823E38 as a floating point constant.
Variables
Variables are names representing values used in the float
ing
point math function blocks. All of the variables you use in a
floating point math function block must be shared variables,
I/O points, or local variables used by floating point math
function blocks only. For example, if you scale an analog
input value to a register, the register should be defined as a
shared variable register if you want to use the scaled result in
a floating point function block.
The floating point math compiler assumes that any local
var
iables found in the function block will be local floating
point registers. If a local variable is used in both a floating
point math and other type of function block, a local data
allocation error will be reported when you attempt to load the
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