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 to a switch.

Inputs

Input	Data Type	Range	Unit	Default	Description
Execute	BOOL	0, 1	N/A	No default	On the rising edge A rising edge is the transition of a digital signal from low to high. It is also called 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. See Axis Name and Number for more information. See AXIS_REF Structure for more information.
TriggerInput	TRIGGER_REF	See Description.	N/A	No default	TRIGGER_REF structure defines the trigger. DirectionINT Range = 1, 2. 1 = Rising edge. 2 = Falling edge. InputID INT Range = 0, 1 0 = Touch Probe 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	LREAL	No range	User unit/sec	No default	Commanded velocity for the reference move.
Acceleration	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 In physics, jerk is the rate of change of acceleration; more precisely, the derivative of acceleration with respect to time 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	LREAL	No range	User units	No default	The position the axis is reset to when at the machine reference location.
Option	SINT	0, 15	N/A	No default	Option identifier for Resolvers/Modulo reference. 0 = Use latched 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 for more information.

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 for more information about how inputs and outputs work.
• See PLCopen Homing for more information.
• If the application selects to reference to the index mark of an encoder, 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.
   • 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 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 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 6-256: 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