Multiple Origins Has Unexpected Behaivior on BB Controller / Solved works as expected using G92 offsets

[Aiph5u (Aiph5u (not affiliated with Onefinity))]

Hey Chris,

G54 is just a coordinate system like the others, with the exception that it is selected after power up. All G54–59.3 commands persist until another of them is given.

You may have a G92 offset in effect before switching to another coordinate system (e.g. to the one selected with G55) and the G92 offset will remain in effect (=the G54–G59.3 coordinate systems add on this then) or you may set G92 later, which will have the same result.

See Coordinate Systems – LinuxCNC.

@Aiph5u

The G-code the Buildbotics Controller (and therefore the Onefinity Controller) uses is patterned after the LinuxCNC dialect, which is patterned after the NIST Next Generation Controller (NGC) Version 3 RS274 Language. The Next Generation Controller (NGC) was succeeded by the Enhanced Machine Controller (EMC) which was then succeeded by LinuxCNC.

@Aiph5u

LinuxCNC evolved from the NIST’s Enhanced Machine Controller (EMC) project (See EMC History).

@Aiph5u

See also: Differences between LinuxCNC and RS274/NGC)

G53 – Move in machine coordinates

@Aiph5u

For moving in machine coordinates, there is the G53 command.

@Aiph5u

G53 Move in machine coordinates – no matter what coordinate system is in effect, it won’t change the latter.

IMPORTANT NOTE: Unlike the coordinate system commands G54–G59.3, G53 is not modal, it must be programmed on each line. G0 or G1 does not have to be programmed on the same line if one is currently active.

For G53 coordinates, on LinuxCNC and controllers with their G-code patterned after the LinuxCNC G-code dialect, there are the parameters #<_abs_x>, #<_abs_y>, #<_abs_z>, #<_abs_a> etc. but they do not work on the Onefinity/Buildbotics controller. A workaround on the Onefinity/Buildbotics is to use [#<_x> + #<_offset_x>]

@ChrisM

then G55 will indeed be set to X10 Y10 away from machine home. But then the G92 global offsets get added to them as well. So they appear to be X10 and Y10 away from where I set the work origin.

Or in other words the G55 ends up being X10 and Y10 away from G54 instead of what I would have expected which is machine home.

But this has nothing to do with G54. G55 is a coordinate system of its own. The offsets are given in machine coordinates and a G92 offset adds to all coordinate systems.