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4.3
GENERAL
SYSTEM
OPERATING
DESCRIPTION
Most
laser
transducer
systems
are
based
on
the
10740A
Coupler
(with
associated
plug-in
modules)
and
a
calculator
or
computer
which
is
used
a s
the
system
controller
and
data
processor.
The
plug-in
modules
interface
the
various
laser
system
components
to
the
coupler
backplane
bus,
and
the
coupler
backplane
bus
carries
all
signals
(data
and
control)
between
the
plug-in
modules.
Basically,
a
counter-based
laser
transducer
system
operates
a s
follows.
Displacement
infor-
mation,
which
is
updated
continuously
in
an
operating
system,
is
transferred,
upon
command,
from
the
counters
on
the
10760A
Counter
plug-in
module
to
the
coupler
backplane
bus.
This
data
is
then
transferred
from
the
bus
to
the
system
controller
for later
processing.
Next,
velocity-
of-light compensation
data
is
transferred
to
the
controller.
The
controller
then
manipulates
the
data
(using
its
processing
capabilities)
so
that
the
raw
data
represents
meaningful
dis-
placement
data.
The
controller
then
outputs
the
data
to
a
printer
or
display
unit
or
compares
the
data
to
predetermined
limits or
setpoints
for
automatic
machine
positioning
applications.
One
of
the
two
plug-in
modules
(either
the
binary
interface
or
the
HP-IB
interface,
depending
upon
specific
application)
is
used
to
interface
the
coupler
backplane
to
thecontrolIer/processor.
The
controller
commands
the
system,
via
the
selected
interface
card,
to
perform
each
function
necessary
to
make
a
measurement.
The
controller
does
this
by
issuing
instructions
that
contain
four
bits
of
module
address
information
and
four
bits
of
module
command
information.
Each
module
in
the
coupler
recognizes
its
unique
address
and
responds
to
commands
associated
with
that
address.
Additionally,
some
modules
automatically
respond
to
commands
sent
to
other modules.
For
example,
when
a
counter
card
is
instructed
to
output
measurement
data
to
the
coupler
backplane
bus,
the
HP-IB
interface
card
automatically
inputs
that
data
and
holds
it
until
instructed
to
output
the
data
to
the
controller
(or
other
device
connected
to
the
HP-IB).
This
feature
allows
faster
processing
of
data
with
fewer
instructions.
The
following
programming
information
describes
the
coupler backplane
instruction
set
that
is
available
to
control
operation
of
a
laser
measurement
system.
Additionally,
sample
programs
are
supplied
to
demonstrate
the sequence
of
operations
required
to
control the
system.
This
information
and
a
thorough
understanding
of
the
system
controller
characteristics
will
allow
you
to
generate
programs
for
your
specific
measurement
application.
4.4
Sample
Outline
for
a
Three-Axis Counter-Based
System
The
following
steps
outline
the
general
programming
requirements
for
a
simple
three-axis
cou
nter-based
system
:
OPERATION
a.
Backplane
Reset
b.
Output
Compensation
c.
Format Data
d.
Read into Calculator
e.
Backplane Sample
f.
Output X-Axis Data
RESULT
Initializes all cards. Presets counters to 160.
Puts compensation data on backplane which
is accepted by 10745A HP-I B Interface.
10745A HP-IB lnterface converts binary data
to BCD and stores in RAM.
Compensation data stored in Calculator.
Samples all counters simultaneously. Puts
counter contents in output buffer.
Puts X-axis data on backplane which is ac-
cepted by 10745A HP-IB Interface.
g.
Format Data
10745A HP-IB lnterface converts binary data
to BCD and stores in RAM.
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