Fuji Electric ALPHA5 Smart, User Manual

Page: 75 / 636

CHAPTER 2 WIRING
Description of I/O Signals
2-27
2
To perform homing, use up positive over-travel [+OT] and negative over-travel [-OT] signals to assure
safety.

Detection of over-travel signal
If homing is started from position A in the figure above, the home position LS is detected and
stoppage is caused.
If homing is started from position B in the figure above, the +OT signal is detected. In this case,
the following motions follow.
(6) Upon detection of +OT, controlled stop is caused according to deceleration time at OT
during homing PA2_18.
(7) A reverse travel begins at the homing speed.
(8) Upon detection of the home position LS, controlled stop is caused. Then the procedure (1)
to (5) described above is executed.

Starting direction for homing (PA2_08)
If homing is executed from B in the figure above, the distance to +OT must be traveled in a round
trip and therefore much time is taken.
If homing is set to negative starting direction, the home position LS will be detected first.

Reverse traveling unit amount for homing (PA2_09)
If homing is executed from B in the figure above, the distance to +OT must be traveled in a round
trip and therefore much time is taken.
If the reverse traveling unit amount for homing is specified, the next action is performed at the
start of homing.
(9) A travel occurs first at the homing speed by the reverse traveling unit amount for homing.
Thereafter the motion (1) to (5) described above is executed.

Reference signal for shift operation (PA2_11)
In regular cases, a travel occurs by the home position shift unit amount in reference to the
encoder Z-phase signal. Stoppage is caused at an accuracy of a single encoder pulse. If the
Z-phase is not used positively due to a reduction ratio of 2 or similar, the home position LS can
be made the standard.
If the moving range is extremely narrow to install a home position LS signal, the +OT and -OT
signals can be referred as the standard.
If a quick response sensor is used instead of the Z-phase of the encoder, the interrupt input
signal can be applied.
Homing direction -OT +OT LS
A B