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4.6
Electrical Circuit Function
4.6.1
Introduction
This section describes electrical circuit functions of the Logic Circuit, Servo
Circuit and R/W Circuit.
Figure 4.6.1 shows the functional block diagram.
4.6.2
Logic circuit
(1)
DE Sequence Control
The drive can execute instructions (TAGl, TAG2, TAG3) sent from the
controller after the START switch on the operator panel is set to ON, the
disk comes up to the rated speed, the head is moved from the CSS area to
cylinder 00 (hereafter called sequence RTZ) , and the drive becomes ready.
The operations performed between the moment the START switch is set to ON
and the moment the drive becomes ready is called the DE Start Sequence.
When the START switch is set to OFF, the drive stops the rotation of the
disk after the head is moved to the CSS area.
The operations performed
between the moment the START switch is set to OFF and the moment the disk
stops is called the DE Stop Sequence.
Each of these sequences is divided into several states (five states for
the DE Start Sequence, and three states for the DE Stop Sequence), which
are determined by decoding DE sequence latches 1, 2, and 4 (hereafter
called DESQLl, DESQL2, and DESQL4) and are named states 0 to 7 (hereafter
called STO
~
ST7).
Figure 4.6.2 shows the states of a drive.
These DE sequences can be monitored by the LEDs on the panel.
a.
DE Start Sequence States
4 -
50
(a)
State 0
When power is turned on, DESQLl, DESQL2, and DESQL4 are reset by
the Initial Reset signal (PWRST).
(b)
State
1
When the START switch on the operator panel is set on ON in
state
0
(STARTS is set high), the start latch (STARTL) is set
and DESQLl is set.
At this time, if the Initial Good signal is
low (INSTG
=
Hall Alarm signal is low (*HALRM) and Motor Speed
signal is low (*MTRSP», the DE sequence check latch (DESQCKL)
is set, DESQLl is reset, and the operation returns to state
O.
When the START switch is set to ON again (OFF
~
ON), DESQCKL is
reset and the operation enters state 1.
B03P-4825-0002A •.• Ol
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