MAS — Motion Axis Stop

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Description

MAS (Motion Axis Stop) brings an axis to a controlled stop. A move in progress is cancelled and the axis decelerates at the Decel rate to standstill; the move’s DN and PC are not set, because it did not reach its target. A jog is ended the same way. The drive stays enabled, so a stepper holds where it stopped. Use MAS for an operator stop, an end-of-travel sensor, or to abort a move when a condition changes. Do not use MAS to end a jog whose rung is still true: MAJ re-issues the jog every scan, so the axis stops and starts again. Release the jog’s rung instead.

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Operands

Operand	Type	Format	Valid Range	Required	Description
Axis	Axis	Axis name	Any axis in Explorer ▸ Axes that has a driver	Yes	The axis to stop.
Decel	REAL	Literal or tag	> 0, in axis units per second squared	Yes	Deceleration rate for the stop. A large value stops harder.

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Scan Behavior

Prescan

Nothing.

Rung-condition-in is false

Nothing. A stop already begun continues to standstill on its own.

Rung-condition-in is true

On this scan and every scan the rung stays true: the pending target and any jog are cancelled and the axis ramps down at Decel. EN clears; IP stays 1 until the ramp ends; DN and PC are not set. The drive remains enabled. On a DC axis the duty is set to 0 and the motor coasts; there is no ramp.

Postscan

Nothing.

Condition	EN	IP	DN / PC	Axis
Move running, MAS true	0	1 while ramping down, then 0	Not set	Decelerates at Decel, holds
Jog running, MAS true, jog rung released	0	1 while ramping down, then 0	Not set	Decelerates at Decel, holds
Jog running, MAS true, jog rung still true	1	1	—	Stops and restarts every scan; release the jog
Axis at rest, MAS true	0	0	Unchanged	Nothing

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Axis Members

Motion status lives on the axis, not on a per-instruction tag.

Member	Data type	Set by	Cleared by	Description
EN	BOOL	MAM, MAJ, MAG while a command is active	Command complete, MAS, MSF	A motion command is engaged.
IP	BOOL	Axis service while steps are being produced	Motion stops	Motion in process.
DN	BOOL	MAM reaching its target, MSR	Next MAM or MAJ	Instruction done. Not set by a stopped move.
PC	BOOL	Same as DN	Same as DN	Process complete.
DriverOn	BOOL	MSO	MSF	The drive is enabled. Not touched by MAS.
InMotion	BOOL	Axis service	Axis service	Steps produced this scan.
Dir	BOOL	Axis service	Axis service	1 = forward.
Error	BOOL	Watchdog mismatch, TMC2130 driver fault	MAFR	Axis fault.
ActualPos	REAL	Axis service every scan	—	Position in axis units; where the stop ended.
CmdPos	REAL	MAM, MAG, MSR	—	Commanded target of the cancelled move (not rewritten by MAS).
Counts	DINT	Axis service every scan	MSR, ResetCounts	Raw step counts.
RedefinePos	REAL	MSR	—	Value of the last MSR.
ResetCounts	BOOL	Your logic (write 1)	Firmware, after zeroing	Zero the counts without an MSR.
Watchdog	INT (ms)	Axis properties; your logic may overwrite	—	Mismatch tolerance before Error sets.

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Example

Scenario: A stop pushbutton aborts whatever the Feed axis is doing, ramping down at 200 mm/s².

Tags:

• Stop_Cmd — Stop command, BOOL
• Feed — stepper axis, 80 counts per mm

Rung 1:

—|XIC Stop_Cmd|———[MAS Feed  Decel 200]———

Scan 1 — Stop_Cmd = 0. A 150 mm move from the MAM page is under way: Feed.IP = 1, Feed.ActualPos climbing.

Scan 2 — Stop_Cmd = 1. The move is cancelled. The axis ramps to a stop and holds; Feed.EN = 0, Feed.IP = 0 once stopped, Feed.DN stays 0.

Values before and after: with the stop pressed one second into the move, Feed.ActualPos ends near 50 mm, Feed.CmdPos still reads 150, Feed.DN = 0. A new MAM edge is needed to continue.

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See Also

• MAM — Motion Axis Move (what MAS usually cancels)
• MAJ — Motion Axis Jog (release its rung to stop a jog)
• MSF — Motion Servo Off (stop and de-energize)
• Motion Instructions — Category index

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Notes

Decel is used for the next move too. The axis keeps Decel as its acceleration setting until the next MAM writes its own Accel. Every MAM sets both, so this only shows if you jog after a stop.

Simulator. The offline simulator stops the axis at once instead of ramping; the members end in the same state.

Servo axis. A hobby servo has no controllable ramp. MAS on a servo axis only clears EN.