The "Configuration" section provides a technical description of what things can be changed in the .$PP file to effect the translation behavior of the postprocessor. The method of changing this file is through the use of a text editor. The text editor must not produce additional control characters. Most word processors require special characters to control formatting. These word processors may also have a mode to suppress these special characters. This mode is known as "programmer's mode". Any text editor that does not produce special characters can be used to edit the .$PP file. The most common is the program named NotePad. It exists in all versions of Microsoft Windows and does not produce special characters. Be sure, however, to turn off Word Wrap as it may format the code improperly.
The postprocessor is a program that reads an AutoCAD drawing exchange file (.DXF) as input and produces numerical control code as output. This translation of a drawing into NC code is controlled by an ASCII text file referred to as the $PP file (the dollar p-p file). This file is usually named after the particular machine tool controller that is being used. Example: Mach1s.$PP or GE550T.$PP
The $PP file is tailored for each particular machine tool/controller combination. It is usually shipped to the user already configured. If you received a preconfigured system, then you may wish to skip this section. It is only provided for the individual who wants to configure the $PP file.
Each line or entry in the $PP file defines a specific translation to the post. At the simplest level an entry consists of NC code on the left of an "=" sign, and the AutoCAD text on the right side of the "=" sign.
This entry in the $PP file indicates that when the text "FINI" statement is processed by the post, it will be translated to "M30" when it is output to the ".NC" file.
Each entry to the right of the "=" sign must be unique. No two text strings on the right of the "=" can be the same.
In the following examples, characters that are boldfaced represent separator or delimiter characters that are used to separate postprocessor information. Throughout the $PP file, the characters '#' and ';' are used to separate switches and strings to control post operation.
Each line or entry in the "$PP" file is structured in one of the three following formats:
1. NC Code Format ; Switches = Text from drawing.
2. NC Code # Format ; Switches = Geometry from drawing.
3. $PP entry # $PP entry = $ Blocktype.
The next three sections explain these different types of postprocessor entries and how they are used to formulate NC code.