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SECTION
9.
INPUT/OUTPUT INSTRUCTIONS
trigger
when measurement goes from above the
limit
to below
it or
when the digital trigger goes
from high to
low.
When
triggering
on
the rising
or
falling edge, the input must make the
specified transition to
trigger.
For example,
when triggering on
the rising edge,
if
the input
starts out high, it must go low and
then high
again to trigger.
DATA SENT
TO INPUT STORAGE
When
the measurements are sent to Input
Storage, Parameter
6
is
used to specify the
number of scans made on the channels being
measured (the
21X multiplies the number
entered
by
1000). The
measurements from
each channel are stored
contiguously. For
example:
Parameter
1
specifies
4
channels are
to
be measured, Parameter
6
specifies 250
scans (0.250 entered),
and Parameter
10
specifies
1
as the
first input location
in
which to
store
data. The
measurements from the
first
channel will be stored
in Input locations
1-250,
those from the second
channel in locations 251-
500,
etc.
lf insufficient locations are allocated to
lnput Storage
(.A) to accommodate the number
of locations called
for by Parameter 6 multiplied
by Parameter
1
(e.9.,
250
x4
=
1000), an
error
code,
E
60, will be displayed when
the program
is
compiled.
The number of scans determines how many
samp,les
will be saved, and hence, when
lnstruction 23
will
be
completed and execution
will pass on to
the next instruction.
Measurements before and/or after the
trigger
can
be
saved.
Parameter
7
determines how
many scans that occurred prior to the trigger are
saved.
For
example ,
it
250
scans are specified,
and an offset of
20
is
entered
for Parameler
7,
then the
trigger measurement will be stored
in
Location
21
.
Locations
1-20
will contain the
measurements
that preceded the trigger
and
22-
250
willcontain the measurements following the
trigger.
lf
only
10
measurements
are made
before the trigger, then they
will
be
stored
in
locations 11-20 while the value -99999.
will
be
stored in locations
1-10
for
which
no
measurements
were made.
DATA SENT
TO SERIAL PORT
When
the
raw
A/D
data
is
sent out the serial
port,
the measurement data is not buffered and
hence, only the
trigger and subsequent
measurements
can be
sent. The
number of
measurements
is
determined
by Parameters
1
and
6.
Because the
total number of
measurements are limited only
by
the storage
o
the receiving computer, this can be
a
very large
number.
Parameter
6
is
the number of
measurements per channel to
send in units of
1000 (e.9.,
0.001 represents
1
measurement).
lf
0
is
entered
for Parameter
6,
the 21X will
continue to send
data
untilthe
instruotion
is
aborted with the
#
key.
Raw
A/D
data may be sent to
up
to
2 SM192 or
SM716 Solid State Storage Modules (SM) at
76.9K baud (parameter
4, Destination Option
C=2).
One SM should be set
as Fill and Stop
memory and
the other SM set as Ring memory.
Data sent will be stored in both SM's (in
pa
untilthe Filland
Stop SM
is
full.
The Fill and
Stop SM
willstore
no more
data. The
Ring SM
will continuously store data, overwriting the
oldest data when
full, until Burst measurements
end.
When
the Burst measurements end the
Fi
and Stop SM
willcontain the oldest data
generated while
the Ring SM will contain the
newest.
l{
the amount of data generated
exceeds the capacity of both SM's only the
oldest and newest data
will
be
saved.
lf
the
amount
of Burst data generated is less then the
total capacity of both SM's, pad
of
the data
stored
will
be
stored in both
SM's.
lf
the data
is
retrieved from
the SM's using SMCOM.COM,
a
Storage Module communications program
contained
in
the PC208 Datalogger Support
Software, the data collection
format must be
"A
as stored 8
bit".
This will transfer
the raw A/D
data to
a
computer
file.
The raw A/D data can
be
converted to
ASCII using SPLIT.COM,
a
general purpose
data reduction program also
contained
in PC208.
lf SPLIT is
not
available for converting
the raw
A,/D,
the following A/D
format information
is
provided for decoding
purposes. At the start
and end
of
the series of measurements, the
21
makes a
self-calibration measurement. The
calibration
data
is
sent
at
the start and end
of
the measurement
data. The serialdata
is sent
as a series of
signed
2byle
integers (most
significant byte sent
first; i.e., Integer
=
256
*
byte
1
+ byte
2):
11...1n.
The
first integer,
1.,,
is
a
start of output identifier, FCxx (hex), where the
first byte
is
always FC (never seen
in
the data),
and
the second byte is a number less than
100
(decimal,
64 hex), which
is
the instruction
9-10
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