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General Mach Discussion / Re: (Mach3) Can't figure out issue with G31 Command (Probing)
« on: July 16, 2022, 05:51:00 PM »
Hi,
this is from the Mach4 API document file. There is no equivalent document for Mach3 but the procedure is almost identical.
Craig
this is from the Mach4 API document file. There is no equivalent document for Mach3 but the procedure is almost identical.
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Probing
Motion plugin probing procedure.
The probe moves are really just G01 moves in exeact stop mode with the addition of being marked as EX_PROBE in the execution_t struct from mcMotionCyclePlannerEx().
When executing a G31, the core considers the move as an exact stop move and therefore will request a motor stop report. It waits on one of two conditions:
A probe strike condition where the motion plugin calls mcMotionSetProbeComplete().
An end of move condition where the motion plugin reports the motors as being still.
Until either of these conditions are satisfied, the core will generate no more moves after the EX_PROBE marked moves. In other words, all you will get out of mcMotionCyclePlannerEx() will be EX_NONE type data. In the event of a probe strike, this makes it safe to clear the planner and be sure that future moves are not removed by accident.
A motion plugin should implement probing in the following way:
Upon seeing the first move marked as EX_PROBE, the plugin should arm position latches on the hardware.
Then consume the EX_PROBE marked moves as normal.
If the probe stikes, the plugin should:
Cancel any motor stop report requests (retrieved from then execution_t::move_t::exMotors structure). (see below. VERY important!)
Report the latched positions via mcMotionSetProbePos() for each motor.
Clear the hardware of any additional moves.
Call mcMotionClearPlanner() to clear the Mach planner of any unretrieved EX_PROBE moves.
Update Mach with the hardware's current position via mcMotionSetPos().
Call mcMotionSetProbeComplete().
If any motor stop report requests has been received, do not acknowledge them. mcMotionSetProbeComplete() does this for you and a position sync as well.
If no probe strike, then the move continues to it's end point as if it is a regular move.
The plugin should ack any motor stop report requests with mcMotionSetStill().
The positions latches should be disarmed (if needed) when a MSG_PROBE_DONE is seen.
In the event that the probe move is aborted, the plugin should:
Call mcMotionClearPlanner() to clear the Mach planner of any unretrieved EX_PROBE moves.
Call mcMotorSetPos() for each controlled motor.
Call mcMotionSync.
Call mcMotionSetStill() for each controlled motor.
Probe Operation Overview.
Upon executing G31, the core will mark those moves as EX_PROBE in the data stream.
If the probe strikes before the end of the G31 move, the plugin aborts the rest of the probe moves as described above. If a probe data file has been opened via mcCntlProbeFileOpen(), then the positions recorded by the motion plugin are inserted into the probe data file in the specified format.
If the probe doesn't strike and the G31 move reaches its end point and a probe data file has been opened via mcCntlProbeFileOpen(), then the end point positions are inserted into the probe data file in the specified format.
Using the probe data file routines.
int mcCntlProbeFileOpen(MINSTANCE inst, const char *filename, const char *format);
The format argument is a printf style format with expanding macros for the axis values. AXIS_X, AXIS_Y, AXIS_Z, AXIS_A, AXIS_B, AXIS_C. It is used in the following manner:
mcCntlProbeFileOpen(inst, "myProbeFile.csv", "%.4AXIS_X, %.4AXIS_Y, %.4AXIS_Z");
This will produce a probe file in CSV format like so:
1.0000, 2.0000, -1.4356
1.0100, 2.0000, -1.4343
1.0200, 2.0000, -1.4324
...
A format of "X%.4AXIS_X, Y%.4AXIS_Y, Z%.4AXIS_Z" would yield:
X1.0000, Y2.0000, Z-1.4356
X1.0100, Y2.0000, Z-1.4343
X1.0200, Y2.0000, Z-1.4324
...
A format of "X%.4AXIS_X\tY%.4AXIS_Y\tZ%.4AXIS_Z" would yield a tab delimited file:
X1.0000 Y2.0000 Z-1.4356
X1.0100 Y2.0000 Z-1.4343
X1.0200 Y2.0000 Z-1.4324
...
int mcCntlProbeFileClose(MINSTANCE inst); Closes the probe data file. Craig