Homing – Yaskawa SMC–4000 User Manual
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SMC–4000 User Manual
Homing
The Find Edge (FE) and Home (HM) instructions are used to home the motor to a mechanical reference.
This reference is connected to the Home input line. The HM command initializes the motor to the
encoder index pulse in addition to the Home input. The configure command (CN) defines polarity of the
home input.
The Find Edge (FE) instruction is useful for initializing the motor to a home switch. The home switch is
connected to the Home input. When the Find Edge command and Begin are used, the motor will
accelerate up to the slew speed and slew until a transition is detected on the homing line. The motor will
then decelerate to a stop. A high deceleration value must be input before the find edge command is
issued for the motor to decelerate rapidly after sensing the home switch. The velocity profile generated is
shown in the following illustration -
Motion intervals in the Home sequence.
The Home (HM) command can be used to position the motor on the index pulse after the home switch is
detected. This allows for finer positioning on initialization. The command sequence HM and BG causes
the following sequence of events to occur.
1.
Upon beginning, the motor accelerates to the slew speed. The direction of its motion is
determined by the homing input. A zero (GND) will cause the motor to start in the forward
direction; +24V will cause it to start in the reverse direction. The CN command defines the
polarity of the home input.
2.
Upon detecting a change in state on the home input, the motor begins decelerating to a stop.
3.
The motor then traverses very slowly back until the home switch toggles again.
4.
The motor then traverses forward until the encoder index pulse is detected.
5.
The SMC–4000 defines the home position as the position at which the index was detected and
sets the encoder reading at this position to zero.
POSITION
POSITION
POSITION
POSITION
POSITION
HOME SWITCH
INDEX PULSES
MOTION REVERSE
TOWARD HOME
DIRECTION
MOTION TOWARD INDEX
DIRECTION
MOTION BEGINS
TOWARD HOME
DIRECTION
Motion intervals in the Home sequence