SMAC
LAC-26 Technical Reference Manual
4/29/2013 55
Command:
CDn
-- Capture Data --
Argument:
0 <= n <=
16383
This command allows for
the
capture
and
recording
of
data
from
an
internal
variable
with
the user being able
to
later
download
and
plot
this data
for analysis.
The
number
of
samples
that
can be recorded depends on the amount of
macro
memory
available
at
the time
that
the
Capture
Storage (CS) command is issued.
The argument
determines
the
number
of samples
to record.
If
an
argument
is
used that
is
greater than the allocated storage space, then the argument will
be
truncated
to
fit
that
space.
A
l
l
data sizes are extended to 32 bits before they are stored.
Before using the CD
command,
a
few things
must
be
taken care
of.
The
first of
these
is
t
o
define
an
area
to
store the
data.
The
Capture
Storage
(CS)
command
is
used for this
in
that
i
t
allocates a storage area in the macro memory
to
where
the
data
can
be
recorded.
The
next
thing
to do
is
to specify
the
location
and
size
of the
data
to be
recorded.
The
internal
16-bit
variable
ÒRecAddrÓ (see Register commands) is used to specify the location (or address) of the
variable
to
b
e
recorded.
The
internal
16-bit
variable
ÒRecSizeÓ
is
used
to
specify
the
data
size.
If
bit
0
o
f
ÒRecSizeÓ is equal to Ò1Ó then
8
bit
data
samples
are
recorded.
If
bit
1
of
ÒRecSizeÓ
is
equal
to
Ò1Ó
then
16
bit
data
samples
are
recorded.
If
bits
0
and
1
of
ÒRecSizeÓ
are
both
Ò0Ó
then
32
data
samples are recorded. The last thing that needs to be specified is the
sample rate at which the data
is captured.
This
is
set by
writing
the
appropriate
value
to
the
16-bit
variable
ÒRecRateÓ.
T
h
e
sample rate will be whatever the servo sample rate is (see SS
command) divided by ÒRecRateÓ.
RecSize
Recorded Variable Size
1
8 Bits
2
16 Bits
0
32 Bits
After using
the
CD
command,
the Dump
Data
(DD)
command
can
be
used to
display
the
data that was captured.
Example:
To
make
2000
records
of
the
actual
position
of
axis
2
you
would
issue
the
following
commands:
CS2000
; Reserve space for 2000 samples.
;
;
;
AL4,WW422
; Servo rate = 1mS so Data rate = 4mS.
AL638,WW424
; Set address of axis 2 Curp.
AL0,WW426
; Set for 32-bit variable size.
The CS command should be used only once. After that, the CD
and
DD
commands
can
b
e
used repeatedly.
Related Commands: CS, DD
