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Macro Basics

Module 10

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Training Manual

Octob er 30, 2001

Invento ry #001571

10-2

10. Macro Basics

One of the most powerful features of APDL (ANSYSParametric Design Language) is the ability to create macros.

A macrois a sequence of ANSYS commands stored in a file

and executed just like a regular command.

Some useful macro capabilities: It can have argumentsas in a standard ANSYS command.

Branching and looping to control the sequence of commands.

Interactive features such as graphical picking, prompting, and

dialog boxes.

Nestedmacros one macro calling a second one, which in turncalls a third one, etc. up to 20 levels deep.

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Training Manual

Octob er 30, 2001

Invento ry #001571

10-3

...Macro Basics

In this chapter, we will present the basics of macro writing:A. Creating a Macro

B. Macro with Arguments

C. Branching

D. Looping

E. General Guidelines

F. Workshop

For more details, please refer to yourAPDL Programmers

Guideor the Programm ing in ANSYS seminar notes.

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Training Manual

Octob er 30, 2001

Invento ry #001571

10-4

Macro B asics

A. Creat ing a Macro

To create a macro, simply start a text editor, insert thedesired sequence of commands, and save them to a file

called name.mac.

namecan be up to 32 characters, starting with a letter.

Spaces are not allowed in the name.

Also avoid special characters. Make sure that nameis not a valid ANSYS command by

typing in nameat Begin level and in all processors (PREP7,

POST1, etc.). If you get the message not a recognized

command or macrothen the name is safe.

Extension .macallows you to execute the macro as if it were acommand by simply typing in name.

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Training Manual

Octob er 30, 2001

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10-5

Macro B asics

...Creating a Macro

Example: A macro totvolume.macto calculate the total volume of all

elements:

esel,all ! Select all elements

etable,volume,volu ! Store volume in element table

ssum ! Sum element table items*get,totvol,ssum,,item,volume ! totvol = sum of volume

*stat,totvol ! List totvol value

Issue totvolumein POST1 (after a solve) to calculate the total

volume.

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Training Manual

Octob er 30, 2001

Invento ry #001571

10-6

Macro B asics

...Creating a Macro

Search Path: ANSYS will execute the first name.macfile it finds in the

following search sequence:

1. /ansys60/docu

2. directory(ies) inANSYS_MACROLIBenvironment variable

3. login directory (home directory on Windows systems)

4. current (working) directory

If the search finds both upper-case and lower-case files of the

same name, the upper-case file is used.

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Training Manual

Octob er 30, 2001

Invento ry #001571

10-7

Macro B asics

B. Macro wi th Arguments

By using special parameter names, you can create a macrowith up to 20 arguments:

NAME, arg1, arg2, arg3, , ar10, ar11, ar12, , ar20

The arguments behave just like the fields on a standard

ANSYS command and can accept:

numbers

alphanumeric characters (enclosed in single quotes)

parameters (scalar or array)

parametric expressions

The meaning of the arguments depends on how you want to

design the macro.

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Training Manual

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10-8

Macro B asics

...Macro w ith A rguments

For example, we could design totvolume.macto calculate thetotal volume for all elements of a specified type:

TOTVOLUME, TYPE

The macro would then look like this:

esel,s,type,,arg1 ! Select elements of specified type

etable,volume,volu ! Store volume in element table

ssum ! Sum element table items

*get,totvol,ssum,,item,volume ! totvol = sum of volume

*vwrite,arg1,totvol ! Write out arg1 and totvol

(Total volume for type , F4.0, elements = , F8.2)

Issuing totvolume,1in POST1 after a solution will then result in:

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Training Manual

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10-9

Macro B asics

...Macro w ith A rguments

Notes:

The special parameter names ARG1-ARG9 and AR10-AR99 arelocal parameters valid only within a macro.

They hold no meaning once the macro has finished executionand control is returned to main ANSYS.

Avoid using these names elsewhere in the model.

Whenever you use arguments, be sure to describe their meaningby including comments in the macro.

For example, the following comments at the beginning oftotvolume.macwould be helpful.

! Macro TOTVOLUME.MAC to calculate total volume of elements

! Usage: TOTVOLUME, TYPE - valid only in POST1 after a solve! TYPE = valid element type number

esel,s,type,,arg1 ! Select elements of specified type

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Training Manual

Octob er 30, 2001

Invento ry #001571

10-10

Macro B asics

C. Branching

By using an IF-THEN-ELSE construct, you can execute a command

or block of commands only if certain conditions are met.

Additional comparison operation are available for the *IF and*ELSEIF commands with AND, OR, or XOR options.

*IF,A,EQ,B,AND,C,GT,D,THEN

Branching begins with *IFand ends with *ENDIF. *ELSEIFand

*ELSEare also allowed in between:*if, x, eq, y, then

*elseif, x, eq, z, then

*else

*endif

*IF constructs can be nested up to twenty levels

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Training Manual

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10-11

Macro B asics

. . .Branching

The condition can be:

x, EQ, y ! x = y

x, NE, y ! x y

x, LT, y ! x < y

x, GT, y ! x > y

x, LE, y ! x y

x, GE, y ! x y

x, ABLT, y ! |x| < |y|

x, ABGT, y ! |x| > |y|

x and y can be numbers,

parameters, or parametric

expressions.

The action can be:

THEN to execute the

subsequent block of

commands*EXIT to exit a do-loop

*CYCLE to skip to the end of a

do-loop

The action takes place only if

the condition is true.Otherwise, ANSYS will move

on to *ELSEIF(if present),

*ELSE(if present), and *ENDIF.

*if, x, eq, y, then

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Training Manual

Octob er 30, 2001

Invento ry #001571

10-12

Macro B asics

. . .Branching

For example, you can add an if-test to totvolume.macto testfor valid values of the input argument:

*if,arg1,lt,1,then ! If arg1 < 1

*msg,warn ! Issue a warning...

Element type number must be 1 or greater

/eof ! and exit the macro

*endifesel,s,type,,arg1 ! Select elements of specified type

etable,volume,volu ! Store volume in element table

ssum ! Sum element table items...

Issuing totvolume,-1will now result in:

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Training Manual

Octob er 30, 2001

Invento ry #001571

10-13

Macro B asics

D. Looping

Do-loops allow you to loop through a block of commands

several times.

There is virtually no limit to what you can include in an

ANSYS do-loop. You can loop through an entire analysis

session including preprocessing, solution, and

postprocessing if the situation warrants it.

*DO or *DOWHILEbegins a loop, *ENDDOends it.

You can control the looping using *EXIT, which exits the do-

loop, and *CYCLE, which skips to the end of the do-loop.

Exitand cyc lecan also be done as a result of an if-test.

As an example, we can extend the totvolume.macmacro to

loop through all element types in the model and store the

volume for each type in an array parameter.

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Training Manual

Octob er 30, 2001

Invento ry #001571

10-14

Macro B asics

. . .Looping

! -- Macro TOTVOLUME.MAC to calculate total element volume.

! -- Usage: Issue TOTVOLUME in POST1 after a solution.

! -- Result:

! -- a) evolume(i) = total volume for element type i

! -- b) totvol = grand total volume

!

*get,numtypes,etype,,num,count ! Get number of element types

*dim,evolume,array,numtypes ! Open a numtypes x 1 array

*do,i,1,numtypes ! For i = 1 - numtypes...

esel,s,type,,i ! Select elements of type i

etable,volume,volu ! Store volume in element table

ssum ! Sum element table items

*get,totvol,ssum,,item,volume ! totvol = sum of volume

evolume(i) = totvol ! Store totvol in evolume(i)

*enddo ! End of do-loop

*vscfun,totvol,sum,evolume(i) ! totvol = grand total volume

esel,all ! Activate full set of elements

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Training Manual

Octob er 30, 2001

Invento ry #001571

10-15

Macro B asics

E. General Guidel ines

Start with small, simple macros.

As you create the macro, remember that you can cut and

pastethe commands into the ANSYS Input window to test

and make sure that the command sequence is correct.

Use comments to describe the intent or expected outcome of

commands.

Place your personal macros in your login directory.

Place company-wide macros in a directory that everyone can

access, and include that directory inANSYS_MACROLIB

environment variable.

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