The postprocessor can translate APT-like text statements from the drawing into NC code. The general format of the entry in the $PP file that is used to translate text is as follows:
NC CODE # FORMAT ; SWITCHES = TEXT
In the above format "#", ";", and "=" are used as separators.
The NC CODE portion of the $PP entry can be a single character or a string of characters that is output as NC Code. Typical codes might be as follows:
G92 X0000.000 Y0000.000 Z0000.000
The FORMAT portion of the $PP entry allows for formatting of the numeric value in the text statement. The format specifies the number of places to the left of the decimal point and the number of places to the right of the decimal point. The first format is used when the postprocessor is in ENGLISH mode (the default). If a second format is encountered, it indicates the format to be used when the postprocessor is in METRIC mode. Each format is separated by the delimiter #. (Most machine tools use different formats for English/Metric code). A typical format would be as follows with 3.4 for ENGLISH and 4.3 for METRIC:
The SWITCHES portion of the $PP entry allows for a wide variety of options concerning formatting and positional placement of the NC Code within the current motion block.
The TEXT portion of the $PP entry that is on the right side of the equal(=) sign is the key that is used to look up and translate the text to NC code. Every text statement in the AutoCAD drawing must have an entry in the $PP file. Each text statement is searched for in the $PP file. When a match is found, the postprocessor translates the text statement into NC code using the parameters described on the left side of the equal(=) sign.