MAFR — Motion Axis Fault Reset

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Description

MAFR (Motion Axis Fault Reset) clears the Error bit of an axis and restarts its watchdog timer. On an axis with a TMC2130 driver it also reads the driver’s fault register, which clears the driver’s own latch, and pulses the Enable line. If the cause is still present the fault returns: a driver fault re-asserts on the next scan, a watchdog fault after another watchdog period. Use MAFR behind a reset pushbutton or a mode change so an operator can acknowledge a fault. Do not hold MAFR true permanently; it would clear every fault the instant it appears and you would never see one.

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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 whose fault is cleared.

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Scan Behavior

Prescan

Nothing. Error is 0 at power-up.

Rung-condition-in is false

Nothing.

Rung-condition-in is true

On this scan and every scan the rung stays true, Error = 0 and the watchdog’s mismatch timer is reset. On a TMC2130 axis the driver’s GSTAT register is read and the Enable pin is pulsed off and on. Nothing else changes: the drive stays as it was, a move or jog in progress continues.

Postscan

Nothing.

What sets Error:

Cause	Detected by	Comes back after MAFR if
Watchdog mismatch: the axis is commanded to move and is not moving, or moving when it should not, for longer than Watchdog ms	Axis service every scan	The mismatch is still there Watchdog ms later
TMC2130 driver fault (over-temperature, short to ground)	Driver service, SPI	The driver still reports the fault on the next read

A step/dir driver without diagnostics can only raise the watchdog cause.

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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
Error	BOOL	Watchdog mismatch, TMC2130 driver fault	MAFR	Axis fault. This is the member MAFR writes.
Watchdog	INT (ms)	Axis properties (default 500); your logic may overwrite	—	Tolerance before a mismatch becomes Error.
DriverOn	BOOL	MSO	MSF	The drive is enabled. Not touched by MAFR.
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.
PC	BOOL	Same as DN	Same as DN	Process complete.
InMotion	BOOL	Axis service	Axis service	Steps produced this scan.
Dir	BOOL	Axis service	Axis service	1 = forward.
ActualPos	REAL	Axis service every scan	—	Position in axis units.
CmdPos	REAL	MAM, MAG, MSR	—	Commanded target in axis units.
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.

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Example

Scenario: A reset pushbutton on the feeder panel acknowledges an axis fault on Feed.

Tags:

• Fault_Reset — Axis fault reset, BOOL
• Feed — stepper axis

Rung 1:

—|XIC Fault_Reset|———[MAFR Feed]———

Scan 1 — Fault_Reset = 0, Feed.Error = 1. The fault stands.

Scan 2 — Fault_Reset = 1. Feed.Error = 0 and the watchdog timer restarts.

Values before and after: Feed.Error 1 → 0. In the offline simulator nothing raises a fault on a plain step/dir axis, so to try this rung set Feed.Error to 1 in the Tag Browser while simulating (axis output members are editable there) and then close Fault_Reset.

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See Also

• MSF — Motion Servo Off (drop the drive on a fault)
• MAS — Motion Axis Stop
• MSO — Motion Servo On
• Motion Instructions — Category index

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Notes

A fault stops nothing by itself. Error is a status bit. The drive stays enabled and a jog keeps jogging. If a fault must drop the axis, write it: XIC Feed.Error → MSF Feed on its own rung.

Pulse it. Put the reset behind a pushbutton or a one-shot. A held MAFR masks every future fault.

Tuning the watchdog. A slow ramp or a heavy load can trip the default 500 ms on a legitimate start. Raise Watchdog in the axis properties, or write the member from the ladder, rather than resetting faults automatically.