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Machine home position return
The FX-1GM PGU has a built-in current value register (storing the absolute address) which is
incremented/decremented by the forward pulse or backward pulse it generates.
This allows the machine position to be calculated at all times.
When the operation is started for the first time,
it
is necessary to teach the current machine position
to the register.
A machine home position return DRV ZRN (DRIVE ZERO RETURN) instruction is prepared to execute
this operation automatically.
DRV ZRN is an independent instruction which is not accompanied
by address instructions, unlike
DRV ABS or DRV
instructions. It is operated in the following sequence:
Switch to turn the motor OFF at
Backward limit
switch
LSR
DOG
f l
L
Home return sequence switch
the forward limit
Motor
Creep speed
J
~
@
Initial position
t
'
Home position return speed
Details
of
machine home
p o s i t i o n r e t u r n a r e
described on page 25.
Pulses of the zero-point signal (PGO) sent from the drive unit to the PGU
are counted, and operations are stopped when the count reaches the
This
point
is
considered
designated
value.
These
pulses
are
normally
1 pulse
per
each
motor
the
home
r
DOG Switch Configurations
Generally, DOG switches are configured as either a single point or a regional signal. In single
point operations, the DOG switch is only switched
ON when the DOG table is at the start of
home return deceleration. Thereafter, it is switched OFF.
DOGSwtchONthmughwtrqon
DOG Switch ON for a
single position
\
;
J
Automatic forward
'
. . . .
.>
. . . . . . . . . . .
'
Manual forward
if the initial position is situated within the O N region of
In the above case, if the DOG table is initially situated
the dog switch, the machine home return operation can
within the home deceleration area, it will not be detected
be executed after advancing to out of range automat-
by the DOG switch. Hence manual forward must be
ically.
driven before the automatic mode can be switched
ON.
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11
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