
3.I/O SIGNALS (CNC ↔ PMC) FANUC AC SPINDLE MOTOR αi series B-65280EN/05
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(b) Zero speed detection signal (SSTA)
(1) When the actual rotation speed of the spindle motor has
decreased to the zero speed detection level or lower for a stop
command, SSTA is set to 1.
(2) The zero speed detection point is 0.75% (initial standard setting
in the parameter) of the maximum speed. For a motor of which
maximum speed is 6000 min
-1
, for example, the zero speed
detection point is 45 min
-1
.
(3) When the above condition is satisfied, this signal is output
regardless of the rotation command (SFR, SRV).
(4) The minimum pulse width of this signal is approximately 40 ms.
(c) Speed detection signal (SDTA)
(1) When the spindle motor speed has decreased to a parameter-set
speed level or lower, SDTA is set to 1.
(2) This signal is used to confirm that the speed has decreased to a
predetermined speed such as a clutch changeable speed or gear
changeable speed.
(3) This signal is output regardless of the rotation command (SFR,
SRV).
<Reference> Gear shift sequence
In CNC machine tools, gear shift, which is one of sequence
controls, causes a shift of the gear section of a spindle, which is
an important component of a machine. In this case, to perform
gear change safely, it is necessary to confirm that the spindle
motor is rotated at a low speed.
A sample gear shift sequence using the speed detection signal
(gear change enable signal) is given below. Please use this
sample as a reference material when designing gear shift power
magnetics sequence.
Zero speed detection
range (standard setting:
±0.75% of the
maximum speed)
SSTA
Motor
speed
0
0
1 1
SDTA
Speed detection
level
Motor
speed