Hi,
In Japan, G31 is described as a skip function.
I don't think that is correct, it is a 'Feed until skip'. This is for example the Fanuc21 interpretation which Mach4 follows closely.
G31 Feed until skip function Used for probes and tool length measurement systems.
The command causes feed, at the prevailing feed rate,
until an event, then
skip the remainder of the move.
If X, Y, Z input the measurement signal to Mach4 before reaching the end point coordinates, Mach4 seems to measure without stopping.
I don't believe this is correct either. Ordinarily Machs Gcode interpreter would have several lines of Gcode in its buffer called look-ahead.
The trajectory planner can therefore do things like blend one move into the next without stopping, called CV mode. With a g31 block however
Mach cannot look-ahead because it has to make a move at the prevailing feed rate
until the probe event, whereon the machine must
stop, the controller must report 'AllStopped' followed by the x,y,z location.....and
abort the remainder of the move. It's this
abortthe remaining move means that Mach cannot have further move instructions in the pipeline because otherwise there would be a time gap between
the probe event and the next scheduled move
after the g31 block. This variable time gap would crash the motion controller which
MUSThave time-continuous move instructions, even if the move instuction is nil, ie 'don't move' but it must get such an instruction every millisecond,
any gap in that stream of instructions will crash the controller.
Craig