Upgrade from NC2 to MC3

Function blocks

NC2 function block	MC3 function block	Note
MC_Power.Enable_Positive MC_Power.Enable_Negative	MC_Power.EnablePositive MC_Power.EnableNegative	Underscore removed
MC_ExtSetPointGenEnable	MC_ActivateExternalSetpointGeneration	Further details on External setpoint generation
MC_ExtSetPointGenDisable	Cancel MC_ActivateExternalSetpointGeneration with an abort command	Example: MC_Halt
MC_ExtSetPointGenFeed	See ITcNcExternalSetpointGeneration
MC_ExtSetPointGenFeedWithTorque	-

MC_GearInDyn	In the Future via MC_GearIn
MC_GearOut		Issuing a motion or hold/stop command to a slave axis disconnects it from the master.
MC_CamOut		Issuing a motion or hold/stop command to a slave axis disconnects it from the master.
MC_Power.Override (Value range in %)	MC_SetOverride.VelocityFactor (Value range normalized to 1)	On the MC3, the override is set to 1 (100%) by default. In Motion UI, values are entered as percentages.
MC_SetPosition.Mode	MC_SetPosition.Relative	Renaming the input for better readability in the code.
MC_Reset	MC_Reset	MC3: Takes effect when the axis is in the Error state. An additional asynchronous reset command for Sercos devices is also triggered and evaluated. `MC_Reset.Done = TRUE`, if the hardware has been reset (including an additional reset for Sercos) and the axis status has changed to “Disabled” or “Standstill.” The position lag is not reset and persists despite the reset command.
MC_Home.bCalibrationCam	See the MC_Home and Homing Modules chapters	Centralized configuration, parameterization, and linking of I/O components in Homing modules
MC_Home.HomingMode := MC_DefaultHoming	MC_Home	MC_Home performs the standard homing procedure configured in the Homing object.
MC_Home.HomingMode := MC_Direct	MC_SetHomingState.Mode := EHomingMode.DirectSetPosition	Additional function block in addition to MC_Home.
MC_Home.HomingMode := MC_ForceCalibration	MC_SetHomingState.Mode := EHomingMode.ForceIsPositionValid	Additional function block in addition to MC_Home.
MC_Home.HomingMode := MC_ResetCalibration	MC_SetHomingState.Mode := EHomingMode.ResetIsPositionValid	Additional function block in addition to MC_Home.
MC_MoveVelocity.InVelocity MC_MoveVelocity.Busy MC_MoveVelocity.Active	MC_MoveVelocity.InVelocity MC_MoveVelocity.Busy MC_MoveVelocity.Active	In the initial situation, the command was sent using `Execute := TRUE`, and `Execute := FALSE` is set again. NC2: `Busy = TRUE, Active = TRUE` and `InVelocity = TRUE` are reset by a falling edge at the Execute input. However, the outputs (especially `InVelocity`) signal TRUE for at least one cycle as soon as the target velocity is reached. MC3: `Busy = TRUE, Active = TRUE` and `InVelocity = TRUE` remain set until the motion command is replaced by another command, even if `Execute` is already set to `FALSE` (PLCopen-compliant).
MC_GearIn.InGear MC_GearIn.Busy MC_GearIn.Active (same as MC_GearInPos)	MC_GearIn.InGear MC_GearIn.Busy MC_GearIn.Active (same as MC_GearInPos)	In the initial situation, the command was sent using `Execute := TRUE`, and `Execute := FALSE` is set again. NC2: `Busy = TRUE, Active = TRUE` and `InGear = TRUE` are reset by a falling edge at the Execute input. However, the outputs (in particular `InGear`) signal TRUE for at least one cycle as soon as the master and slave axes move in sync with each other. MC3: `Busy = TRUE, Active = TRUE` and `InGear = TRUE` remain set until the motion command is replaced by another command, even if `Execute` is already set to `FALSE` (PLCopen-compliant).

Re-triggering an MC function block using MC_MoveAbsolute as an example

VAR
    axis_nc2 : TC2_MC2.AXIS_REF;
    axis_mc3 : Tc3_Mc3Ptp.AXIS_REF;

    move_absolute_mc3 : Tc3_Mc3Ptp.MC_MoveAbsolute;
    move_absolute_nc2_1 : Tc2_MC2.MC_MoveAbsolute;
    move_absolute_nc2_2 : Tc2_MC2.MC_MoveAbsolute;
END_VAR

CASE step OF
    0:
        // MC3 init movement
        move_absolute_mc3(Axis := axis_mc3, Position := 111, Execute := TRUE);

        // NC2 init movement
        move_absolute_nc2_1(Axis := axis_nc2, Position := 111, Velocity := 100, Execute := TRUE);

        step := step + 1;

    1:
        // MC3 retrigger same FB instance during one cycle
        move_absolute_mc3 (Axis := axis_mc3, Position := 111, Velocity := 100, Execute := FALSE);
        move_absolute_mc3 (Axis := axis_mc3, Position := 222, Velocity := 100, Execute := TRUE);

        // NC2 use additional FB instance
        move_absolute_nc2_1(Axis := axis_nc2, Position := 111, Velocity := 100,Execute := FALSE);
        move_absolute_nc2_2(Axis := axis_nc2, Position := 222, Velocity := 100,Execute := TRUE);
        step := step + 1;
END_CASE

	Re-triggering an MC function block using MC_MoveAbsolute as an example In NC2, if the `Execute` input is triggered again while the command is being executed, the function block does not provide any feedback, nor does it execute any further commands. This restriction does not apply to MC3. If the `Execute` input is triggered again while the command is running, the new parameters are applied and the function block is re-executed according to the buffer mode. This can be done within a single PLC cycle. For example, the first call to `Execute := FALSE` (changing from TRUE to FALSE) is `fbMyMoveAbsolute(Axis := ax, Execute := FALSE, Position := 111)`, and immediately following that is the second call to the same block instance with a new position: `fbMyMoveAbsolute(Axis := ax, Execute := TRUE, Position := 222)`.

Status

NC2	MC3	Note
myAxisRef.Status.IoDataInvalid	myAxisRef.McToPlc.Std.AxisState	PLCopen state diagram expanded (states: Invalid, NotReady, Enabling, Disabling). Example: The axis remains in the NotReady state if the drive hardware is not ready (see the State Diagram chapter)
myAxisRef.Status.Homed	AxisRef.McToPlc.Std.IsPositionValid	`IsPositionValid` also takes into account, for example, the state of the axis's driven object (CoE drive input: `Position actual value invalid`). If the axis starts up using, among other things, an absolute encoder, the axis has a unique reference position and reports `IsPositionValid := TRUE.`
myAxisRef.ReadStatus()	myAxisRef.McToPlc.Std	Status information can be retrieved directly from the CDT `Std`.

NC2

MC3

Note

myAxisRef.Status.IoDataInvalid

myAxisRef.McToPlc.Std.AxisState

PLCopen state diagram expanded (states: Invalid, NotReady, Enabling, Disabling).

Example: The axis remains in the NotReady state if the drive hardware is not ready (see the State Diagram chapter)

myAxisRef.Status.Homed

AxisRef.McToPlc.Std.IsPositionValid

IsPositionValid also takes into account, for example, the state of the axis's driven object (CoE drive input: Position actual value invalid). If the axis starts up using, among other things, an absolute encoder, the axis has a unique reference position and reports IsPositionValid := TRUE.

myAxisRef.ReadStatus()

myAxisRef.McToPlc.Std

Status information can be retrieved directly from the CDT Std.

Error at the drive hardware level or missing communication

The starting point is the transition of the TwinCAT system from Config to Run. This occurs when the drive hardware is in an error state or communication via the EtherCAT fieldbus is disrupted.

NC2: An axis error is displayed when MC_Power.Enable = TRUE. In addition, you can check for communication issues, for example, via myAxisRef.Status.IoDataInvalid .
MC3: Once communication between the axis and the drive is established, the drive status and any errors are evaluated immediately and, if necessary, displayed as axis errors. The state diagram for the MC3 axis has been expanded compared to the NC2 and PLCopen (states: Invalid, NotReady, Enabling, Disabling). The MC3's axis status can be used to centrally monitor its state.

Example 1: If MC_Power.Enable := FALSE and communication with the drive is not possible, the axis status remains in the state myAxisRef.McToPlc.Std.AxisState = EAxisState.NotReady.
Example 2: If MC_Power.Enable := FALSE and the drive is in an error state, then the MC3 axis reports myAxisRef.McToPlc.Std.AxisState = EAxisState.ErrorStop.