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Omron SYSMAC C Series User Manual

Omron SYSMAC C Series
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Scan
time
Scan
time
calculation
examples
When
calculating
the
total
scan
time
required
by
the
PC
to
perform
its
internal
operations,
the
system
configuration
must
be
taken
into
consid-
eration.
This
means
factoring
into
the
calculation
such
things
as
the
number
of
input/output
units
and
specia!
instructions,
and
whether
peripheral
devices
are
employed.
For
example,
let's
see
how
to
calculate
the
scan
time
when
the
PC
is
used
by
itself
and
with
no
special
instructions.
For
the
sake
of
simplicity,
it
is
assumed
the
user
program
consists
of
512
addresses
and
only
uses
the
LD
and
OUT
instructions.
Of
the
four
parameters
for
the
calculation
(the
times
required
for
common
processes,
data
input/output,
instruction
execution,
and
servicing
peripheral
device
commands),
how
long
it
takes
to
perform
the
common
processes
and
service
peripheral
device
commands
are
fixed
at
1.07ms
and
1.1ms,
respectively.
This
leaves
only
the
remaining
two
parameters
to
be
calculated.
The
time
required
for
data
input/output
can
be
determined
by
using
the
following
equation
where
the
variable
N
can
be
0,
1,
or
2
depending
on
whether
an
V/O
unit
is
connected
to
the
PC
and
which
I/O
unit
it
is.
Data
input/output
time
=
1.04ms
+
0.33ms
x
N
Since
in
this
example
we
assume
that
the
C20
is
used
by
itself,
the
value
of
constant
N
equals
0.
Thus,
1.04ms
+
(0.33ms
x
0)
=
1.04ms
Next,
the
time
required
for
executing
all
the
instructions
in
the
program
must
be
known.
To
do
this,
obtain
the
average
execution
time
and
then
multiply
that
time
by
the
number
of
addresses
in
the
program.
Because
only
the
LD
and
OUT
instructions
are
used
in
this
example,
the
average
instruction
execution
time
can
be
obtained
by
adding
the
execution
times
for
the
two
types
of
instructions
and
then
dividing
the
sum
by
two.
To
find
the
execution
times
for
these
two
instructions,
refer
to
“List
of
instruction
execution
times”
on
the
preceding
pages.
We
see
from
this
list
that
the
execution
time
of
the
LD
instruction
is
12us
and
that
of
the
OUT
instruction
is
17.5us.
Accordingly,
the
average.execution
time
is:
(12us
+
17.5yus)/2
=
14.75us
Now
it
is
possible
to
obtain
the
total
instruction
execution
time
by
multiplying
14.75us
by
512,
the
number
of
program
addresses.

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Omron SYSMAC C Series Specifications

General IconGeneral
BrandOmron
ModelSYSMAC C Series
CategoryController
LanguageEnglish

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