MC_TouchProbe

 Function Block A function block groups an algorithm and a set of private data. It has inputs and outputs. - Arms a Fast Input The inputs are taken into account at each cycle depending on the system periodicity (i.e., each millisecond). Under certain circumstances, this can be insufficient when more accuracy is needed or if a quick response is required from the system. To fill the gap, a drive may have some Fast Input connections (generally one or two). When an event happens that triggers a Fast Input (e.g., when a sensor sends a rising edge), the detection of a signal occurs faster. This can be 1000 times more accurate than the system periodicity. The timestamp associated with this input can be provided to the IPC to take corrective action. and returns the 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 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. when the Fast Input event occurs.

Inputs

Elements

Capture Engine

This is the 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. capture engine to be used.

INT TriggerInput.InputID

InputID INT

Range = 0, 1

• 0 = Touch Probe See Softscope - Probe item. 1 / Capture Engine 0
• 1 = Touch Probe 2 / Capture Engine 1

Trigger Direction

This is the input signal’s edge to capture.

INT TriggerInput.Direction The orientation components of a vector in space.

Range = 1, 2

• 1 = Rising edge.
• 2 = Falling edge.

• 
  
• Trigger Direction is also sent to the servo drive A special electric amplifier used to power electric servo motors. It monitors feedback signals from the motor and continually adjusts for deviation from expected behavior. and is shown in the WorkBench Position Capture screen Edge setup.

Axis Number

This is where the input comes from.

INT TriggerInput.TrigID

Range = 0, 256.

0 = Trigger axis is to be the same as Axis.AXIS_NUM.

Trigger Mode

This is the capture method.

INT TriggerInput.TrigMode

Range = 0, 1

• 0 = Time based capture.
• 1 = Position based capture.
  • For position based capture, the TrigID must be the same as the AXIS_REF.

• 
  
  
• The Mode (either Time or Position) must be configured the same in the servo drive.
  This can be done either in:
  
  • COE Init commands and executed when the EtherCAT Ethernet ofr Control Automation Technology. EtherCAT® is an open, high-performance Ethernet-based fieldbus system. The development goal of EtherCAT is to apply Ethernet to automation applications which require short data update times (also called cycle times) with low communication jitter (for synchronization purposes) and low hardware costs. network is initialized (0x3460, subindex 3 and 4).
  • The WorkBench Positon Capture screen.

Outputs

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.

• This function or function block does not generate any motion.
• See Function Blocks - General Rules about how inputs and outputs work.
• This function block captures an axis position
• When the Execute input transitions from low to high, the control requests the drive to arm its Fast Input to latch the axis position when a Fast Input occurs.
• The Axis input specifies which axis's position to latch and the TriggerInput input specifies which Fast Input to use and whether to trigger on the rising or falling edge of the Fast Input.
• When the Fast Input event occurs, the drive latches the axis's position.
  • This function block then returns the latched position at the RecordedPosition output and set the Done output high.
  • This process can be canceled with the AbortTrigger function block.
• If the WindowOnly input is high, the FirstPosition input and the LastPosition input define a window in which a Fast Input is accepted.
• Any Fast Input events that occur outside the window is ignored.

• 
  
• There are differences in how MC_TouchProbe interacts with AKD and AKD2G drives.
  See these topics for drive-specific information:
  • AKD Support With MC_TouchProbe
  • AKD2G Support With MC_TouchProbe

• 
  

• The accuracy Accuracy is the distance between the actual position of a mechanical system and the expected position. It is typically specified in microns or arcsec per given travel for a deviation of ±3 (sigma). of captured position data depends on the travel 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. Please see the article MC_TouchProbe and Time-Based Capture on KDN for more information and how to correct for timing.

Example 1

If First Position ≤ LastPosition, the window in which a Fast Input is accepted is:

FastInputPosition ≥ FirstPosition AND FastInputPosition ≤ LastPosition

Example 2

If First Position > LastPosition, the window in which a Fast Input is accepted is:

FastInputPosition ≥ FirstPosition OR FastInputPosition ≤ LastPosition

This image shows the ladder diagram view of the MC_TouchProbe function block:

Figure 1: MC_TouchProbe

Fast Homing - Inputs

See these topics for more information:

• Fast Homing Example with the Pipe Network Motion Engine Axis Pipe Block
• Fast Homing Example with the PLCopen Motion Engine
• Fast Inputs with Pipe Network Motion
• Pipe Network Registration and Fast Homing
• Registration Position Capture Example with Pipe Network Trigger Block

Usage

This function block can be used to:

• Perform registration
• Determine the position of a product
• Measure product length

Limitations

• Both high speed Speed is the absolute value of the velocity without direction. inputs cannot be used at the same time.
• The TrigMode option is only used by MC_TouchProbe.

FBD Language Example

Not available.

FFLD Language Example

IL Language Example

Not available.

ST Language Example

(* MC_TouchProbe ST example *)
TriggerInputRef.InputID := 1;    //configure InputID
TriggerInputRef.Direction := 1;  //configure Direction
TriggerInputRef.TrigID := 0;     //configure TrigID
TriggerInputRef.TrigMode := 0;     //Capture trigger based on distributed clock Clock signal. time
Inst_MC_TouchProbe( ArmProbe, Axis1, TriggerInputRef, FALSE,0.0, 0.0 );
//Inst_MC_TouchProbe is an instance of MC_TouchProbe function block
ProbeIsDone := Inst_MC_TouchProbe.Done;            //store Done output into a user defined variable
ProbeValue := Inst_MC_TouchProbe.RecordedPosition; //store RecordedPosition output into a user defined variable

See Also

MC_AbortTrigger