Re: gcode comments

Alan,

The ";" used to be the standard way to end a block of gcode. This was
before pc-based controls. Nowadays, the CR,LF combination is the
standard. (Carriage Return,Line Feed) But it may be worthwhile to
allow the semicolon, for backwards compatibility. As I mentioned, the
semicolon is still the standard for HPGL files.

The "/" character is called "optional block delete". Or "optional
block skip". Or "block skip". Or "slash code".
Most older controls REQUIRED this "slash code" when used, to be the
first character on the line/block. Some new controls allow its' use
within a block, which can be VERY useful! (more later)

The way it works is:

When the control parser reads a "/" character, it skips the remainder
of the line/block, IF the "Block Delete" switch (which is on the
control panel) is SET. If the panel switch is not set, the "/" has no
effect.

This is like the M01 "optional stop".

(it's later)

One useful way to use block skip is to drill, or not drill, in
related but disimilar parts. You just put a slash in front of
the "extra" holes. If the switch is set, these lines will be skipped
and the holes won't be drilled.

Another useful way to use slash codes/block delete is to change
feeds/speeds when making the same part from different materials. You
just use the F word and S word as usual, BUT you put two
different 'instances' on each line where you want to change feed or
speed. For example:

G01 x5 y3 F15 S500 / F75 S2500

Now most controls which support mid-line/block "/" will set F to 75
and S to 2500, if the switch is OFF(since the parser usually replaces
until the last parameter is read). If the switch is on, these codes
are not read and the F15 and S500 will be used.

pretty cool, huh!

You can use a variation of this technique to "add-in" roughing passes
when machining castings, based on operator evaluation...

Hope this helps.

Ballendo

P.S. I tried to get Tom to implement this in EMC, but last I checked,
he hadn't...

>So is the ';' not advisable? I want to implement the "stock size"
>also. I have also read (NIST ?) that '/' can be used to "comment
>out" a line. Is this in general acceptance? I like the '()'
>comments, easy to parse.