What does the Post_Base command do

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Model of CNC Machine: Stepcraft D420

What does the Post_Base command do

Post by Martingchapman »

Been looking into Post Processor files.
Specifically the "Stepcraft_UCCNC_Arcs_mm.pp" file, as I have a Stepcraft machine.
The contents of this file are below -

+ Stepcraft (UCCNC Controller)
+ Vectric machine output configuration file
+ History
+ Who When What
+ ======== ========== ===========================
+ Tony 15/11/2005 Written for metric
+ Tony 06/01/2006 Added ATC option
+ Tony 14/05/2006 Fixed G21 mm in header
+ Tony 24/07/2006 Added G2 & G3 Arc support + removed (( ))
+ Tony 18/06/2007 Replaced the Tool comment
+ Mark 14/08/2008 Added G1 to Feed moves,
+ Mark 28/08/2009 Added G91.1 to force use of incremental arcs
+ Mark 30/11/2009 Added TOOLPATHS_OUTPUT.
+ Brian 15/12/2009 Remove M05 from NEW_SEGMENT
+ Mark 18/01/2014 Added Dwell
+ Mark 01/09/2016 Named for Stepcraft
+ EdwardP 17/12/2018 Original post used for UCCNC base
+ Derived this one from general case

POST_NAME = "Stepcraft UCCNC Arcs(mm)(*.txt)"



The POST_BASE command above is the last one in the file, there are no others, so how does this Post Processor work?
Is it that the POST_BASE command is like a subroutine "call" command that calls the named file into operation, ie this pp calls the "UCCNC_mm.pp" post processor and runs that pp.
I made a copy of the Stepcraft_UCCNC_Arcs_mm.pp file and moved it to the "My_PostP" folder so that it is the only .pp that is offered when I go to save a toolpath, and saving a toolpath still works.
So is the POST_BASE command calling the UCCNC_mm.pp file, even though this file is in a different folder.

Would appreciate an explanation of how this works please.


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Re: What does the Post_Base command do

Post by Adrian »

It's not documented in the post processor editing guide but I would assume it's an inheritance type directive. Especially as the comments for the UCCNC_mm post processor say it's directly copied from the Stepcraft UCCNC Arcs(mm) one.

It would save having multiple copies of what are essentially the same lumps of code. The GRBL based post processors do the same thing. You can add any commands that are specific to your needs after the POST_BASE command.

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Re: What does the Post_Base command do

Post by mohamed »

Exactly what Adrian said. Any sections or variables you add to the derived post will override / replace the ones in the base post.

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