Omron TJ2-MC64 - PROGRAMMING Programming Manual page 286

Examples and tips
Note
If a forward limit, reverse limit and origin input signal are used for
an axis, it is strongly recommended to use the following settings
for the axis:
BASE(axis_number)
DAT_IN=18
' /DEC input in the corresponding Servo Driver is
' assigned
FWD_IN=16
INVERT_IN(16,ON)
' P_OT input in the corresponding Servo Driver is
' assigned. It is necessary to invert the signal
' because a Normally Closed input is expected.
REV_IN=17
INVERT_IN(17,ON)
' N_OT input in the corresponding Servo Driver is
' assigned. It is necessary to invert the signal
' because a Normally Closed input is expected
Also note that INVERT_IN inverts the selected input in all axes.
5.1.5 Origin search
The origin search or homing functionality is often seen as a particular
sequence of movements of an axis at the start-up phase of the machine.
This sequence is done automatically in most cases, without the input from
the operator of the machine. In general, an origin search procedure couples
a position to a specific axis. It depends on the encoders used (absolute or
relative), on the system used (linear or circular), and on the mechanical
construction of the machine. Absolute encoders do not need a movement
during the origin search procedure, because the exact positions are
transferred directly to the system. For other encoder types, a movement is
necessary, since there is no knowledge of the exact position within the
PROGRAMMING MANUAL 280