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3.
1
.
SPECIFICATIONS
1
fWt3EC-A
3.3
General Desariptlon
of
P o s R h l n g System Operations
This section gives a general description of the
AlSD71 and its use in a
positioning system.
3.3.1
Positioning system using
an
AlSD71
Fig. 3.1 shows :the operation of an A1 SD71 in a positioning system.
PC
CPU
module
Positioning
(AlSCPU)
A1SD71 Forward pulse
Drive unit
Servo motor
---------
string
-wu
Speed
4
command
I
D-A
-
Error
counter
converter
*
Program
o:
-
Set
i
data
c)
.
a
7
'
.-
-
interface
Reverse
:
pulse
h ; - ,
write+
string
U -
t
Feedback pulse
-LnnT
---------
--
Peripheral
device.
AD71TU
Servo motor speed
I
Time
t
Fig. 3.1 Posltioning System Operation
Block Diagram
The AlSD7l's output is a pulse string
When pulse strings are output, pulses are converted into error counters.
Deviation counter pulse values are converted into DC analog voltages by a
D-A converter, and changed into speed commands.
The drive unit gives a speed command.
The motor begins to rotate and the pulse generator
PG
gives feedback pulses
in proportion to the revolutions of the motor to subtract accumulated pulses.
The motor rotation continues maintaining the constant deviation counter pulse
value.
When the command pulse output
from the AlSD71 ceases, the deviation
counter pulse value decreases, and the speed slows down.
Then, when the deviation counter pulse value becomes 0, the motor stops.
Thus, the motor's rotary speed is proportional to the frequency
of the com-
,
mand pulse, and degree of the angle of the motor's rotation is proportional to
the number of command pulse output pukes.
Therefore, transmission can be done to a position that is proportional to the
number
of
pu1se.s of a pulse string by specifying the feedrate per pulse.
The pulse frequency is equal to
the number
of revolutions (transmission
speed) of the motor.
3 - 5
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