MC_Reference

 Function Block A function block groups an algorithm and a set of private data. It has inputs and outputs. - Used to execute a fast home The homing procedure allows, based on a position measurement, to set a position offset to the motor to ensure it is physically at the home position. to a switch.

Inputs

Input	Data Type	Range	Unit	Default	Description
Execute	BOOL	0, 1	N/A	No default	On the rising edge The transition of a digital signal from low to high. AKA: positive edge., request to queue the move and arms reference trigger events.
Axis	AXIS_REF	1, 256	N/A	No default	Name of a declared instance of the AXIS_REF library function A function calculates a result according to the current value of its inputs. A function has no internal data and is not linked to declared instances.. See Axis Name and Number. See AXIS_REF Structure.
TriggerInput	TRIGGER_REF	See Description.	N/A	No default	TRIGGER_REF structure defines the trigger. Direction The orientation components of a vector in space.INT Range = 1, 2. 1 = Rising edge. 2 = Falling edge. InputID INT Range = 0, 1 0 = Touch Probe See Softscope - Probe item. 1 / Capture Engine 0 1 = Touch Probe 2 / Capture Engine 1 TrigidINT Must be 0 (zero). TrigMode INT (TriggerInput.TrigMode) is not presently supported by this function.
Velocity For a group of axes this means: In ACS the velocities of the different axes. In MCS and PCS it provides the velocity of the TCP	LREAL	No range	User unit/sec	No default	Commanded velocity for the reference move.
Acceleration A change in velocity over time. Because velocity is a vector, it can change in two ways: a change in magnitude and/or a change in direction. In one dimension, acceleration is the rate at which something speeds up or slows down. However, more generally, acceleration is a vector quantity expressing the change with time of the velocity both in magnitude and in direction. See these Wikipedia articles for more information: http://en.wikipedia.org/wiki/Velocity http://en.wikipedia.org/wiki/Euclidean_vector http://en.wikipedia.org/wiki/Rate_(mathematics)	LREAL	no r	User unit/sec2	No default	Commanded acceleration for the reference move.
Deceleration	LREAL	no r	User unit/sec2	No default	Commanded deceleration for the reference move.
Jerk In physics, jerk is the rate of change of acceleration. More precisely, the derivative of acceleration with respect to time.	LREAL	No range	User unit/sec3	No default	Commanded jerk for the reference move. If 0 (zero), the trapezoidal acc/dec is used.
Direction	SINT	0, 1	N/A	No default	Commanded direction of the reference.
Position Position means a point in space which is described by different coordinates. Depending on the used system and transformation it can consist of a maximum of six dimensions (coordinates).This means three Cartesian coordinates in space and coordinates for the orientation. In ACS there can be even more than six coordinates. If the same position is described in different coordinate systems the values of the coordinates are different.	LREAL	No range	User units	No default	The position the axis is reset New start of the microprocessor. to when at the machine The complete assembly of all connected parts or devices, of which at least one is movable. reference location.
Option	SINT	0, 15	N/A	No default	Option identifier for Resolvers/Modulo reference. 0 = Use latched The control word is used to activate the drive's latch status machine. The latch control word is processed independently of the EtherCAT® bus cycle. The status word is used to return the drive's latch status. position for reference. 1 = Use resolver position of nearest null for reference 2 pole resolver. 2 = Use resolver position of nearest null for reference 4 pole resolver. 3 = Use resolver position of nearest null for reference 6 pole resolver. 4 = Use resolver position of nearest null for reference 8 pole resolver. 5 = Use resolver position of nearest null for reference 10 pole resolver. … 15 = Use resolver position of nearest null for reference 30 pole resolver.

Outputs

Output	Data Type	Range	Unit	Description
Done	BOOL			Indicates the reference move and position adjustment is complete.
Busy	BOOL			Indicates this function block is executing.
Active	BOOL			Indicates this move is the Active move.
CommandAborted	BOOL			Indicates the move was aborted.
Error	BOOL			Indicates either: An invalid input was specified. The move was terminated due to an error.
ErrorID	INT			Indicates the error if Error output is high. See PLCopen Function Block ErrorIDs.

Remarks

• 
  
• This function block starts a motion-related action and stores data for calculations and error checking.
  See Call Function Blocks Multiple Times in the Same Cycle if using a dual-core controller.

• 
  

• At this time, position capture is not available for PLCopen axes assigned to the secondary feedback input (digitizing axes).
  MC_Reference cannot be used to home digitizing axes.

• See Function Blocks - General Rules about how inputs and outputs work.
• See PLCopen Homing for more information.
• If the application selects to reference to the index Zero pulse (zero signal) of a hardware pin such as digital input or feedback pin. mark of an encoder Generates an output signal directly proportional to the movement of the motor shaft. This signal is fed into the control circuitry to control the shaft position and speed. The most common types are: Incremental/Serial encoders, Hall effect sensors, Resolvers, Tachometer Generators See: Optical encoders., or the null of a resolver (which is typical), the new position value is assigned to the position of the index of the encoder (or the null of the resolver) and not the position of the switch.
• The ECATWriteSDO function block is used to setup the trigger event and any desired preconditions.
• This function block utilizes the Position Capture Mode of the AKD.

• 
  
• There are a differences between how an AKD and an AKD2G are used with this function block.
  • AKD Support With MC_TouchProbe
  • AKD2G Support With MC_TouchProbe

Usage

• 
  

• Once the MC_Reference block is queued, but before it is completed, the cycle can be aborted by either:

  • Using a MC_Halt or MC_Stop function block.
  • By queuing a new motion function block with the Abort selected for buffer mode.
    • See Buffer Modes for more information.

These are steps for homing a PLCopen axis using the MC_Reference function block.

Not all of the steps are necessary depending on the configuration and the homing cycle design.

1. Verify the Axis is not on Reference switch An adjustable hardware switch for indicating a home position..
   • If a switch is used in the homing cycle for the event or precondition to the event, verify the axis is not already tripping the switches that trigger the event and precondition.
   • If it is, move the axis off the switches.
2. Configure the AKD capture engine.
   • Configuration of the AKD capture engine is performed by writing drive In electrical engineering, a drive is an electronic device to provide power to a motor or servo. Control device for regulating the speed, torque and position of a motor. A unit controlling a motor using the current and timing in its coils. CAN Controller area network - CAN is a broadcast, differential serial bus standard developed for connecting electronic control units. Each node is able to send and receive messages, but not simultaneously. objects via SDO.
   • Use the ECATWriteSdo function for this action.
     • The AKD Capture mode must be set to POSITION CAPTURE.
   • See AKD Capture Engine Configuration for information about the available configurations.
   • See PLCopen Homing Methods for example AKD capture engine configurations and references.
3. Call the MC_Reference function to initiate optional homing motion and to arm the AKD capture engine.
   • MC_Reference selects the trigger edge (rising or falling edge) and arms the capture.
   • Then, it optionally moves the axis to the reference location as directed by inputs to this function.
   • When the AKD indicates the capture event has occurred, the coordinate system The reference system in which a coordinate or path is described. is shifted so the reference position input to this function block is set to the reference location and the reference motion is stopped.
4. Wait for the completion of the MC_Reference function block.
   • The application is notified by the completion, abort, or error of the homing by the MC_Reference function block.
5. When the MC_Reference function block is completed, the axis can be moved to the home position with a MC_MoveAbsolute function block.

Figure 1: MC_Reference

FBD Language Example

Not available.

FFLD Language Example

IL Language Example

Not available.

ST Language Example

(* MC_Reference ST example *)
TriggerInput.InputID := 0;    //configure the reference InputID
TriggerInput.DIRECTION := 1;  //configure the reference direction
Inst_MC_Reference( RefReq, Axis1, TriggerInput, 20.0, 100.0, 100.0, 100.0, 0, 0.0, 0 );

See Also

• ECATWriteSdo
• MC_MoveAbsolute