Reference Manual

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PMAC 2 Software Reference

278 PMAC On-Line Command Specification

PMATCH

Function

Re-match Axis Positions to Motor Positions

Scope

Coordinate-system specific

Syntax

PMATCH

Remarks

This command causes PMAC to recalculate the axis starting positions for the coordinate

system to match the current motor commanded positions (by inverting the axis definition

statement equations and solving for the axis position).

Normally this does not need to be done. However, if a motor move function, such as a jog

move, an open-loop move, or a stop on abort or limit, was done since the last axis move or

home, PMAC will not automatically know that the axis position has changed. If an axis

move is then attempted without the use of the PMATCH command, PMAC will use the wrong

axis starting point in its calculations.

Also, with an absolute sensor, a PMATCH command should be executed before the first

programmed move, so the starting axis position matches the (non-zero) motor position.

If the PMATCH function is not performed, PMAC will use the last axis destination position as

the starting point for its upcoming axis move calculations, which is not necessarily the same

position as the current commanded motor positions.

The PMATCH function can be executed from within a motion program using CMD”PMATCH”

with DWELLs both before and after. This is useful if the coordinate system setup changes in

the middle of the program (e.g. new axis brought in, or following mode changed).

If more than one motor is defined to a given axis (as in a gantry system), the commanded

position of the lower-numbered motor is used in the PMAC calculations.

Note:

If I14 is set to 1, the PMATCH function will be executed automatically

every time program execution is started. Most users will want to use

I14=1 so they do not have to worry about when this needs to be done.

Example

#1J+.................. ; Jog motor 1

#1J/.................. ; Stop jogging

PMATCH............. ; Match axis position to current motor position

B200R ............... ; Execute program 200

OPEN PROG 10 CLEAR

...

CMD”&1#4->100C” ; Bring C-axis into coordinate system

DWELL100

CMD”PMATCH”. ; Issue PMATCH so C-axis has proper start position

DWELL100

C90