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4.3.4. Automatic Home position calibration

This feature is used for detection and placing the movement to the starting position. This option of the controller is designed for simple
search of "Home", or "Zero" position by user himself, with no need of any programming skills. The Home position is set relative to one
or two external sensors and/or to an external signal.

Automatic Home position calibration feature is configured by user in Device configuration->Home position folder of XILab software (see
the

Home position settings

chapter) and is activated by the button in

XiLab main window

After  this  feature  is  activated,  the  controller  rotates  the  motor  to  the  defined  direction  with  normal  speed  to  quickly  locate  the  stop
position.  After  finding  the  boundary  position  controller  assigns  motor  back  half  a  turn  and  begins  rotate  the  motor  to  the  defined
direction,  but  with  another  calibration  speed.  The  calibration  speed  is  usually  set  lower  than  the  normal  rotation  speed  in  order  to
improve  the  calibration  accuracy.  There  are  three  ways  to  determine  the  completion  of  the  motion,  according  to  user-defined
preferences:

rotation until the

limit switch

is reached, the actual configuration of limit switches is used (e.g., polarity, location). For more

details please refer to

Motion range and limit switches

chapter.

rotation until a signal from the

synchronization input

is received, the actual configuration of synchronization input is

used. For more details please refer to

Synchronization settings

chapter. If the synchronization input is switched off by program,

the signal from it will never be processed.
rotation until a signal from the

revolution sensor

is received, the actual configuration of revolution sensor is used. For

more details please refer to

Position control

chapter.

Successful completion of home position calibration results in assertion of the STATE_IS_HOMED flag in the

controller state structure

. If

after this position somehow got lost (stop on

while moving,

, turns the

the corresponding flag is dropped and it is necessary to re-calibrate the home position.

Note. If command

emergency stop

or command

power shutdown

are executed while the engine is stopped then it

isn't necessary to re-calibrate the home position and the STATE_IS_HOMED flag is not dropped.

Note. If the completion of the motion should happen at the limit switch, the calibration program is not crashed.

Fine calibration

After the first displacement the controller position is defined. However, some additional rotation may probably get turned on before the
movement to Home position is performed. It provides fine Home position calibration that may reach 1/256 of the step for stages with
stepper motors or 1 encoder count for stages with DC motors. If the corresponding flag is switched on, the controller rotates the motor
to user-defined direction with defined rotation speed until a signal either from the

synchronization input

or from the

revolution sensor

is received or until the

limit switch

is reached, according to user-defined preferences. Using the signal from the sensor on the shaft

from motor to reducer and performing the motion with the small speed does make sense. It provides the maximum accuracy. Since
first and second movement signals might happen simultaneously a flag is provided, which will start tracking second motion end signal
only after motor shaft half-turn. This allows avoiding the signals of the completion of the first and second motions to be in ambiguous
sequence. As a result of optional second motion, the calibrating position becomes more accurate.

Note. If the second phase of the motion is used, the first motion usually can be performed at the high speed since it
provides just a coarse calibration and the accuracy is not required there. The accuracy will not improve if the second
limit switch is used for the second phase of the motion since its physical characteristics are the same as for the first
limit switch.

Finally the controller moves the motor to the defined direction with the defined speed at the defined Standoff distance. This is what
required to reach the Home position.

Note. The position reached as a result of calibration will slightly depend on the speed of the last motion until the
selected sensor responsed. Therefore, don't change the speed parameters for further successful reaching the same
position.

The automatic Home position calibration features are described in the

Programming guide

chapter.

The parameters configuration commands are described in the

Communication protocol specification

chapter

The position calibration command is described in the

Communication protocol specification

chapter.

A set_zero

script

is supplied with XiLab software pack, providing the automatic Home position configuration. This script changes the