bCNC allow to use python inside gCode. Proceed a line with the % symbol and the line will be evaluated by the sender.

There are some special directives:

• %wait : empty and wait the grbl buffer. It will pauses the internal sender until all commands up to this point are completed, grbl return "ok" and the Rx grbl buffer is empty.
• %if running : executed only when code is streamed to grbl. Not during editing.
• %msg :
• %update :
• #nnn : access to internal variables