M6 remap in pure python lessons learned

bazhenov4job wrote:

Yeah, I saw the way you call prolog procedure inside the remap function.
Back to the question.
As well as you do I would like to remap M6 command using pure python. U use the interpreter module, emccanon module and linucxnx mudule. For linuxcnc documentation is easy to find and it's pretty good. But for the interpreter module and for emccanon I couldn't find the documentation.
For example, a description of self.params dicirionary is implicit, as well as **words argument.
That is what I hoped you've found and can share with me))

It has been several years since I wrote that code. The machine is still working btw. The documentation I struggled with because there is not alot of info on remapping in pure python. Most of the remapping is geared towards ngc remaps. There are bits and pieces in the remap docs that help. Otherwise you have to look at examples and source code.

The Remap extending Gcode,  section 8. configuring embedded python  has some good info.
You can also try contacting the author of the Remap Michael Halber, (I think his name is), over at MachineKit. I tried contacting him and he never responded, I dont think he is interested in responding to linuxcnc questions on remapping. The MachinKit forum has some topics on remapping in python also.

But all in all, the basic structure is in the docs but the details are in the source code, and your trying different things.

So you have to pull bits and pieces from the ngc remap docs like below. 
re: remap docs:9.5. Calling conventions: Python to NGCNGC code is executed from Python when:

• the method 

  self.execute(<NGC code>[,<line number>])

   is executed
• during execution of a remapped code, if a 

  prolog=

   function is defined, the NGC procedure given in 

  ngc=

   is executed immediately thereafter.

The prolog handler does not call the handler, but it prepares its call environment, for instance by setting up predefined local parameters.
Inserting parameters in a prolog, and retrieving them in an epilogConceptually a prolog and an epilog execute at the same call level like the O-word procedure, that is: after the subroutine call is set up, and before the subroutine endsub or return.This means that any local variable created in a prolog will be a local variable in the O-word procedure, and any local variables created in the O-word procedure are still accessible when the epilog executes.The  array handles reading and setting numbered and named parameters. If a named parameter begins with  (underscore), it is assumed to be a global parameter; if not, it is local to the calling procedure. Also, numbered parameters in the range 1..30 are treated like local variables; their original values are restored on return/endsub from an O-word procedure.Here is an example remapped code demonstrating insertion and extraction of parameters into/from the O-word procedure:

I've given up in trying to format this forums posts. It comes out the way it wants to. Sorry for the confusion above in the way it is formatted.

Here is some more:

Extending LinuxCNC

3.3.3 Named Params passing to python function
3.3.4. Advanced example: Remapped codes in pure Python  
 

Thanks a lot for your notes!

There is some customization in our device that is hard (or maybe impossible) to drive using standart NGC procedures, mostly based on state analysys on tool change and other remappable codes.

ok well, just a hint, try and keep things as simple as possible. Just don't go too deep with nested functions as the interpreter will start ignoring commands.

Also do exhaustive testing, as simple things like having two or three toolchanges in a gcode file  may not work as expected. So make sure you test this stuff well.

May be there is something you can help me to deal with.

I'm trying to read mist and flood state during my remap procedure using linuxcnc.stat() object. But when I run my .ngc file to execute, the state of mist and flood measured equals to its state on the begining of the execution, not on the moment I really want them to be measured. In other words, my script is readahead. I tried to use INTERP_EXEC_FINISH to performe a queuebreaker operation, but failed. Is there any moments in usage of INTERP_EXEC_FINISH you faced and solved, similarly to mine one?

Not sure I can be of any help here as most of this is not documented very well. You have to work through it.

Are you polling when requesting the status?
 

Yes, I do.

The interpreter just performs poll simulteneously  to I click "run" button.

You can check an input in a pure python remap.