B–65195EN/01
6. SERVO CHECK BOARD
START-UP PROCEDURE
33
b7 b6 b5 b4 b3 b2 b1 b0
1956
8X12
VCM2 VCM1
2012
VCM2 VCM1 Specified speed / 5V
0 0 0.9155 rpm
0 1 14 rpm
1 0 234 rpm
1 1 3750 rpm
To check small vibrations, monitor the entire vibration on the DC
mode of the ascilloscope then enlarge monitor the desired range on
the AC mode.
GND
DC mode
Enlarge
AC mode
VCMD
GND
E
1/f
When the signal conversion result for the VCMD waveform is W (rpm/5
V), the voltage per positional shift pulse is:
Voltage (V) per positional deviation pulse =
300 _ Position gain (S
–1
)
Number of positional feedback pulses/motor revolution _ W
(Example)
Assume the conditions: Position gain = 30 (S
–1
), the number of positional
feedback pulses/motor revolution = 1000 pulses, and signal conversion
result for the VCMD waveform = 14 rpm/5 V with 1 µm/pulse)
Under these conditions, if you observe E = 300 mV and 1/f = 20 ms:
Voltage per positional deviation pulse = 64 mv/pulse
Therefore, table vibration = 300 _ 1/64 = 4.6 µm, with a vibration
period of 50 Hz
(6) TCMD signal
The TCMD signal outputs a motor torque command. It may be
different from the actual current (IR, IS) of the motor rotating at high
speed, because the motor produces a back electromotive force.