Statements

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Post Processor Statements

 

How Variables Are Substituted

 

Statements are defined in a configuration file to describe the output for a machine movement.  Statements take the format of:

 

FEED_RATE_MOVE = "G01 [X] [Y] [Z] [F]"

 

The exact content will vary depending on the desired output but the formats are similar.  On the left-hand side of the equal sign is the statement name.  The names are predefined by MeshCAM; other names are not allowed.  The right-hand side is the string to be written to the output file when the post processor writes the statement.  The quotes are not required and are not written to the output.

 

Variables in the statements appear between brackets.  Like statement names, the variable names are predefined and other variables are not allowed.  When a statement is called the variables are substituted with their numeric values, as defined by their corresponding FORMAT statements, and the resulting string is written to the output file.  After each line, a carriage return is added to the output.

 

Tool Moves

 

There are five types of tool moves in MeshCAM:

 

1.The first move at the feed rate
2.Subsequent moves at the feed rate
3.The first move at the rapid rate
4.Subsequent moves at the rapid rate
5.Retract moves.

 

Five statements define the moves listed above:

 

1.FIRST_FEED_RATE_MOVE
2.FEED_RATE_MOVE.
3.FIRST_RAPID_RATE_MOVE
4.RAPID_RATE_MOVE
5.RETRACT_MOVE

 

Of the five statements above only the second, FEED_RATE_MOVE, is required.  The rest are optional and may or may not be required for your machine.  It is best to look at the two primary categories of moves individually in the following sections.

 

Linear Moves

 

Linear moves are those that involve the tool engaging the material to be removed.  As noted above, there are two statements describing these moves, FIRST_FEED_RATE_MOVE and FEED_RATE_MOVE.  The FEED_RATE_MOVE statement is required to be present in every post processor configuration file.  If FIRST_FEED_RATE_MOVE is present in the configuration then it is used for the first linear move and FEED_RATE_MOVE is used for all following linear moves until a retract or rapid move is encountered.  The following illustrates several scenarios.

 

FORMAT = [X|#|X|1.2]

FORMAT = [Y|#|Y|1.2]

FORMAT = [Z|#|Z|1.2]

FEED_RATE_MOVE = "[X][Y][Z]"

 

 

Coordinates

Output        

0,0,0 Feedrate=10

G01 X0.00Y0.00Z0.00F10

1,0,0

G01 X1.00

1,1,0

G01 Y1.00

 

FORMAT = [X|#|X|1.2]

FORMAT = [Y|#|Y|1.2]

FORMAT = [Z|#|Z|1.2]

FIRST_FEED_RATE_MOVE = "G01 [X][Y][Z][F]"

FEED_RATE_MOVE = "[X][Y][Z]"

 

Coordinates

Output

0,0,0 Feedrate=10

G01 X0.00Y0.00Z0.00F10

1,0,0

X1.00

1,1,0

Y1.00

 

Rapid Moves

 

Rapid moves are formatted in a way similar to linear moves.  Rapid moves add two statements, FIRST_RAPID_RATE_MOVE, and RAPID_RATE_MOVE.  Both of these are optional.  If they are omitted then rapid moves are processed as linear moves.

 

Plunge Moves

 

Plunge moves are processed using the PLUNGE_RATE_MOVE statement.  It is an optional statement.  If it is missing then plunge rate moves are processed as linear moves.

 

Arc Moves

 

A post processor configuration may optionally support arc moves if their machine controller support them.  The statements are:

 

FIRST_CW_ARC_MOVE

FIRST_CCW_ARC_MOVE

 

CW_ARC_MOVE

CCW_ARC_MOVE

 

The standard usage of these statements are:

 

FIRST_CW_ARC_MOVE = "G2[X][Y][I][J][F]"

CW_ARC_MOVE = "G2[X][Y][I][J]"

;

FIRST_CCW_ARC_MOVE = "G3[X][Y][I][J][F]"

CCW_ARC_MOVE = "G3[X][Y][I][J]"

 

If a post processor configuration file does not define these statements then any arcs are automatically converted back to linear moves.

 

 

Other Statements

 

Statement

Use

COMMENT_START        

Defines the text the precedes any comments placed in the output.

COMMENT_END

Defines the text placed after comments placed in the output.