G2/G3 Error 32: No axis words in plane (too strict rule)

[kimstik]

I found potential issue in vanilla GRBL https://github.com/gnea/grbl/issues/1178

grblHAL have similar in gcode.c

                    if (!(axis_words.mask & (bit(plane.axis_0)|bit(plane.axis_1))))
                        FAIL(Status_GcodeNoAxisWordsInPlane); // [No axis words in plane]

[terjeio]

Change to

                    if (gc_block.words.r && !(axis_words.mask & (bit(plane.axis_0)|bit(plane.axis_1))))
                        FAIL(Status_GcodeNoAxisWordsInPlane); // [No axis words in plane]

to fix?

[kimstik]

your fix will make sense for R-mode only ? original check is correct in Arc mode and non-valid in helix mode where in-plane begin and end coordinates is same .

[terjeio]

your fix will make sense for R-mode only ?

No, the check will only be performed for R format arcs, from LinuxCNC specs:

"It is an error if:

• both of the axis words for the axes of the selected plane are omitted"

For center format arcs the check is not required as error 33 will be reported if parameters are incorrect?

[terjeio]

Ref 3.5.3.2 Center Format Arc in NIST RS247NGC:

"It is an error if: • X and Y are both omitted, • I and J are both omitted."

etc...

Thus Grbl and grblHAL is compliant with the NIST spec, LinuxCNC is not? I do not have LinuxCNC instance to check with so cannot verify this. So for now I will leave the code as-is.

[kimstik]

it seems you are right. Following case is not compliant with "NIST RS274NGC Interpreter" specs:

G17
G2 X7 Y0 Z-1 I-7 J0
Z-2 I-7 J0

In terms of NIST interpreter this code is erroneous.

another point is: What is reason to not execute code if is [logic, complete and comprehensive] but not NIST compliant ? Do I missing something?

Actually i do not see reason to do exception for arcs, and specify coordinate words which not changes. Sounds like useless code noise.