Motion Servo Off (MSF)
This information applies to the
CompactLogix
5370, ControlLogix
5570, Compact GuardLogix
5370, GuardLogix
5570, Compact GuardLogix
5380, CompactLogix
5380, CompactLogix
5480, ControlLogix
5580, and GuardLogix
5580 controllers. Controller differences are noted where applicable.Use the Motion Servo Off (MSF) instruction to deactivate the drive output for the specified axis and to deactivate the axis' servo loop.
IMPORTANT:
If you execute an MSF instruction while the axis is moving, the axis coasts to an uncontrolled stop.
Architecture | Standard | Safety |
---|---|---|
CompactLogix 5370, ControlLogix 5570, Compact GuardLogix 5370, and GuardLogix 5570 controllers | Yes | No |
Compact GuardLogix 5380, CompactLogix 5380, CompactLogix 5480, ControlLogix 5580, and GuardLogix 5580 controller | Yes | No |
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
Operand | Type CompactLogix 5370, Compact GuardLogix 5370, Compact GuardLogix 5380, CompactLogix 5380, CompactLogix 5480 | Type ControlLogix 5570, GuardLogix 5570, ControlLogix 5580, and GuardLogix 5580 controllers | Format | Description |
---|---|---|---|---|
Axis | AXIS_CIP_DRIVE | AXIS_CIP_DRIVE AXIS_GENERIC AXIS_GENERIC_DRIVE AXIS_SERVO AXIS_SERVO_DRIVE Tip: AXIS_GENERIC is supported by the ControlLogix 5570 and the GuardLogix 5570 controllers only. | Tag | Name of the axis on which to perform operation. For controllers that support the REF_TO motion data types, the supported axis operand type can be replaced by an equivalent REF_TO type. |
Motion Control | MOTION_INSTRUCTION | MOTION_INSTRUCTION | Tag | Structure used to access instruction status parameters. |
See
Structured Text Syntax
for more information on the syntax of expressions within structured text.MOTION_INSTRUCTION Structure
Mnemonic | Description |
---|---|
.EN (Enable) Bit 31 | It is set when the rung makes a false-to-true transition and remains set until the servo message transaction is completed and the rung goes false. |
.DN (Done) Bit 29 | It is set when the axis’ servo action has been successfully disabled and the drive enable and servo active status bits have been cleared. |
.ER (Done) Bit 28 | It is set to indicate that the instruction detected an error, such as if you specified an unconfigured axis. |
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.
IMPORTANT:
The instruction execution may take multiple scans to execute because it requires multiple coarse updates to complete the request. The Done (.DN) bit is not set immediately, but only after the request is completed.
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
Condition | Ladder Diagram Action |
---|---|
Prescan | The .EN, .DN, and .ER bits are cleared. The rung-condition-out is set to false. |
Rung-condition-in is false | The .EN bit is cleared if the .DN or .ER bit is true. |
Rung-condition-in is true | The .EN bit is cleared to false if the .DN or .ER bit is true |
Postscan | The rung-condition-out is set to false. |
Structured Text
Condition/State | Action Taken |
---|---|
Prescan | See Prescan in the Ladder Diagram table |
Normal execution | See Rung-condition-in is false, followed by rung is true in the Ladder Diagram table. |
Postscan | See Postscan in the Ladder Diagram table. |
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
Bit Name | State | Meaning |
---|---|---|
ServoActionStatus | FALSE | Axis is in Servo Off state with the servo loop inactive. |
DriveEnableStatus | FALSE | Axis Drive Enable output is active. |
Motion Status Bits
Bit Name | State | Meaning |
---|---|---|
AccelStatus | FALSE | Axis is not Accelerating. |
DecelStatus | FALSE | Axis is not Decelerating. |
MoveStatus | FALSE | Axis is not Moving. |
JogStatus | FALSE | Axis is not Jogging. |
GearingStatus | FALSE | Axis is not Gearing. |
HomingStatus | FALSE | Axis is not Homing. |
StoppingStatus | FALSE | Axis is not Stopping. |
PositionCamStatus | FALSE | Axis is not Position Camming. |
TimeCamStatus | FALSE | Axis is not Time Camming. |
PositionCamPendingStatus | FALSE | Axis does not have a Position Cam Pending. |
TimeCamPendingStatus | FALSE | Axis does not have a Time Cam Pending. |
GearingLockStatus | FALSE | Axis is not in a Gear Locked condition. |
PositionCamLockStatus | FALSE | Axis is not in a Cam Locked condition. |
DirectVelocityControlStatus | FALSE | Axis is not under Direct Velocity Control. |
DirectTorqueControlStatus | FALSE | Axis is not under Direct Torque Control. |
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);
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