Open topic with navigation

Fast Homing Example with the Pipe Network Motion Engine Axis Pipe Block

This use case explains how to use the motion library functions of the axes when you want to detect the positive edge of the first Fast InputThe inputs are taken into account at each cycle depending on the system periodicity (for example 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 (which can be 1000 times more accurate than the system periodicity). Then the timestamp associated with this input can be provided to the IPC to take corrective action in the drive, and read its associated timestampA timestamp is a sequence of characters, denoting the date and/or time at which a certain event occurred. MLAxisIsTrigged can be used to accurately perform a homing procedure in a user-defined procedure.

A Setup sequence example.

1. MLAxisCfgFastIn(PipeNetwork.AXIS1, MLFI_FIRST, MLFI_RISING_EDGE)
• Configure Fast Input 0 of AXIS1 to be triggered on the positive edge.
  • 
    

  • Since tMLFI_FIRST and MLFI_SECOND correspond to the physical Fast InputsThe inputs are taken into account at each cycle depending on the system periodicity (for example 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 (which can be 1000 times more accurate than the system periodicity). Then the timestamp associated with this input can be provided to the IPC to take corrective action 1 and 2. Therefore the drive must be configured in order to link fast inputThe inputs are taken into account at each cycle depending on the system periodicity (for example 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 (which can be 1000 times more accurate than the system periodicity). Then the timestamp associated with this input can be provided to the IPC to take corrective action 1 with engine 0, and fast input 2 with engine 1.

• The first argument indicates the Axis pipe block in the Pipe Network that represents the drive to be configured
• The second argument identifies which of the two Fast Inputs of the drive is configured (can be 0 or 1)
• The third argument can indicate detection of positive edge when set to 1 and detection of negative edge when set to 2
  Note that if set to 0, Fast Input is disabled
2. MLAxisIsTrigged(PipeNetwork.AXIS1, 0, 1)
• This function returns true if Fast Input 0 of AXIS1 has been triggered on the positive edge.
• The meaning of the arguments is the same as in MLAxisCfgFastIn
3. MLAxisTimeStamp(PipeNetwork.AXIS1, 0, 1)
• This function returns the time in microseconds when the Fast Input was triggered on the positive edge
  This time is relative to the start of the drive cycle time and its value is explained in the section How To Interpret a Timestamp.
• The meaning of the arguments is the same as in MLAxisCfgFastIn
4. MLAxisRstFastIn(PipeNetwork.AXIS1, MLFI_FIRST)
• This function resets the Fast Input 0 of AXIS1. The reset keeps the configuration of the Fast Input, but it rearms it so it can be triggered again
• The meaning of the first two arguments is the same as in MLAxisCfgFastIn
5. Follow-up Motion

The following is typical code used in a homing procedure.

CASE StepCounter OF

0:

MLAxisRstFastIn(PipeNetwork.Feeder,MLFI_FIRST);

MLAxisMoveVel(PipeNetwork.Feeder,250.0); //Jog Feeder Axis to search for sensorA sensor is a type of transducer that converts one type of energy into another for various purposes including measurement or information transfer input

StepCounter := 1;

1:

IF MLAxisIsTrigged(PipeNetwork.Feeder,MLFI_FIRST,MLFI_RISING_EDGE)
   THEN MLAxisAbs(PipeNetwork.Feeder,MLAxisCmdPos(PipeNetwork.Feeder)); //Stop motion when sensor is reached
   StepCounter := 2;
END_IF;

2:

IF MLAxisGenIsRdy(PipeNetwork.Feeder)
   THEN MLAxisWritePos(PipeNetwork.Feeder,0); //Set Feeder Axis position to zero
   StepCounter := 3;
END_IF;

Fast HomingThe Homing procedure allows, based on a position measurement, to set a position offset to the motor in order to ensure it is physically at the home position based on the drive's high speed capture mechanism is also supported by the following Kollmorgen KUDFBs in the IDE"Integrated development environment" An integrated development environment is a type of computer software that assists computer programmers in developing software. IDEs normally consist of a source code editor, a compiler and/or interpreter, build-automation tools, and a debugger Function BlockA function block groups an algorithm and a set of private data. It has inputs and outputs. Library: MLFB_HomeFindHomeFastInput, MLFB_HomeFindHomeFastInputModulo, , and MLFB_HomeFindLimitFastInputModulo.

The Axis Position can also be derived from the Time Stamp by with the following code:

TimeStamp := any_to_lreal(MLAxisTimeStamp( iAxisID, any_to_dint(ibFastInputNumber), 1+any_to_dint(ibHomeSwitchMode) ))/1000000;
CalculatedTriggerPosition := (CurrentVelocity-PreviousVelocity)/2/iCycleTime*TimeStamp*TimeStamp+PreviousVelocity*TimeStamp+PreviousPosition;

Stay Connected with Kollmorgen

Copyright © 2015 Kollmorgen™

Open topic with navigation