Motion Servo Off (MSF)

Use the Motion Servo Off (MSF) instruction to deactivate the drive output for the specified axis and to deactivate the axis' servo loop.

Available Languages

Ladder Diagram

Function Block

This instruction is not available in function block.

Structured Text

MSF (Axis,MotionControl);

Operands

Ladder Diagram and Structured Text

See

Structured Text Syntax

for more information on the syntax of expressions within structured text.

MOTION_INSTRUCTION Structure

Description

The MSF instruction directly and immediately turns off drive output and disables the servo loop on any physical servo axis. With non-CIP motion, this places the axis in the Axis Ready state described in Motion State Instructions. With CIP motion, this places the axis in the Stopped state described in Motion State Instructions. The MSF instruction also disables any motion planners that may be active at the time of execution. The MSF instruction requires no parameters – simply enter or select the desired axis.

If the targeted axis does not appear in the list of available axes, the axis has not been configured for operation. Use the Tag Editor to create and configure a new axis.

You can use the MSF instruction to turn servo action off when you must move the axis by hand. Since the position continues to be tracked even with servo action off. When the servo loop is turned on again, by the Motion Servo On (MSO) instruction, the axis is again under closed-loop control, at the new position.

The axis stopping behavior varies depending upon the type of drive. In some cases the axis coasts to a stop and in other cases the axis decelerates to a stop using the drive’s available stopping torque.

For non-CIP motion, to execute an MSF instruction successfully, the targeted axis must be configured as a Servo axis. If this condition is not met, the instruction errs. If you have an Axis Type of Virtual the instructions errors because with a Virtual Axis the servo action and drive enable status are forced to always be true. A Consumed axis data type also errors because only the producing controller can change the state of a consumed axis.

Additionally, for CIP motion, the MSF instruction supports canceling the Motion Drive Start (MDS) instruction. This includes clearing the MDS In Process (.IP) bit, and clearing the DirectVelocityControlStatus bit and the DirectTorqueControlStatus bit in the Motion Status attribute.

In this transitional instruction, the relay ladder, toggle the Rung-condition-in from cleared to set each time the instruction should execute.

Master Driven Speed Control (MDSC) and the MSF Instruction

If an MSF is issued in Master Driven Mode, the system shuts the servo off.

The IP bit of the Master Driven Axis Control (MDAC) instruction does not change on an axis that has its servos turned off.

The AC bit of the MDAC instruction resets when the axis stops as the servos are turned off.

Affects Math Status Flags

No

Major/Minor Faults

None specific to this instruction. A major fault can occur if an uninitialized reference or a reference of the incorrect type is passed to the Axis operand. See

Common Attributes

for operand-related faults.

Execution

Ladder Diagram

Structured Text

Error Codes

See

Motion Error Codes (.ERR)

for Motion Instructions.

Extended Error Codes

Extended Error Codes provide additional instruction specific information for the Error Codes that are generic to many instructions.

MSF Changes to Status Bits

Axis Status Bits

Motion Status Bits

Example

When the input conditions are true, the controller disables the servo drive and the axis servo loop configured by Axis0.

Ladder Diagram

Structured Text

MSF(myAxis, myMotionControl);

Relay Ladder

Structured Text

MSF(Axis_01,MSF_1);