Test; Analog Output; General; Description - Datron 1061 Calibration And Servicing Handbook

3.6.4
Test
.-When
TEST
is
selected,
the ratio option
is
checked
to
see
if it
¡s
fitted, uv int
-r-ró.iing
il.,u
AD4 line
to
see
if
it
is
held
high.
3.7
ANALoc ouTpuT
(circuit
Drawing
No.430308)
3.7.1
General
The Analog
Output
Board
accepts
the DC lsolator or
AC
Converter Output
and converts
it to
a
Jl
volt
DC
full
range
output.
This signal
can
then
be used,
for example,
to
drive X-Y plotters or
strip
chart
recorders.
3.7.2
Description
The
3.16V
full
range signal
from the DC
lsolator or
AC
Converter is buffered by unity
gain
amplifier M2. The
output is potentially divided by
R7 and
RB
so
that
1
volt
full
range
is presented
to
M1, another
unity gain
amplifier.
Potentiometer R5
is adjusted
to
remove
any
offset
caused
by
M1 and M2.
Positive temperature coefficient
thermis-
tors
R3,
R4
and diodes
D1
,D2,
protect
the
Analog
Output
circuitry
from
accidental
input
applied
to
the
Analog
Ougut
external connector.
3.8
DIGITAL
ASSEMBLY
(Circuit
Drawing
No.430329)
The Digital
assembly contains the
circuitry
providing
the
general management
of
the
instrument and the digital
section
of
the A-D converter. Fig.
3.33 outlines
the
main
portions
and signal highways
of
this
board.
3.9.1
processor and
Memory
(430329
sheet
l
)
A
6900
microprocessor (MpU)
together
wirh l6k
bytes
of
memory controls the
commun¡cai¡on between the
front
panel,
digital
interface, display
drivers,
Digital
and
analog
assemblies.
The
memory can be
split into
five
main areas:-
-l
(11
Program
Memory
needed
to operate the
whole instrument
system.
33
(2)
Constant
Data
Memory
(31
Non-volatile
Calibration
Memory
(41
Operating Memory
(5)
Volatile Display
Memory
e.g.
Self Test
limits'
Error
read-out
sPecif
ic'
ations and
other fixed
factors.
used
to
store
all the
calibration errors used
for
each reading
and
determined
during
the
'Auto-cal'
cycle.
used
for
scratch
Pad
operations and storing.
volatile
data such
as
Max-Min stores,
Limit
stores
and computation
store
s.
DATA
LATCHES
ANALOG
INTERFACE
DIGITAL
SECTION
OF
A-D
r/o
BUFFER
KS
MPU
POWER
UP/
DOWN
MEMORY
FIG.3.33 SIMPLIFIED BLOCK DIAGRAM
OF
DIGITAL
ASSEMBLY
DISPLAY DIGITAL
DRIVER
INTERFACE
ASSY.
ASSY.
',ì