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Model
34SSA
Section
111
3-8t. Statdi
Bytt
M«t»
9
e.
The
status
byte
message
is
output
by
the
34SSA
in
response
to
a
serial
poll
and
in-
dicates,
to
the
controller,
the
nature of
a
service request
message
(SRQ) from
the
34SSA.
The
following
is
a
list
of
the
basic status
byte codes
output by
the
34SSA;
Status
Byte
Code
ASCII
^
,
CHAR
A
6S
Data
Ready
•
indicates to the
con-
troller
that
rneasuremeni data
is
available.
Applies
to
DATA
READY
Request
feature.
B
66
Syntax Error
-
Indicates
improper
1
program
code.
Example
Pro-
gram
Code "F7"
would
cause
a
,
syntax
error
since
the
FUNC-
1
TION
program
set
is
only defined
for
codes FI through
F6.
D
68
1
'
BINARY FUNCTION
Error
-
In-
dicates
improper
BINARY
PRO-
GRAM
code
or
incomplete
binary
message. Similar to syntax
error.
H
!
72
Trigger
too
Fast
•
Indicates the
3455A
has been
triggered while
measurement
data
is
being output
to the
bus.
Warns
of
possible
in-
correct
measurement
information.
it is
possible for
more
than
one
of
the basic
status
byte
messages
to
be
true.
In
this
case the resulting status byte
code would
be
the
combinttuion of
the basic status byte
codes being
output.
As
an example,
the
resulting
ct^e
for
the
combination of
the
syntax
error
and
trigger
too
fast
messages
would
be
ASCII
character
J
decimal
code
74.
The
following
illustrates
the status
Byte
message
in-
dicating the
purpose of each
relevant
"bit".
STATUS BYTE MESSAGE
3-B2.
DATA OUTPUT
CHAFIACTERISTICS.
3-83.
The
protocol used by
the
34SSA
to
output
measurement
data
must be
followed
in
order
to preserve
proper data
transfer
over
the
HP-IB,
the
following
notes
on
data
transfer
over
the
HP-IB may
be
helpful:
a.
If
a reading
has been taken
and
thus
resides
in
the
output
buffer, the
buffer
is
not considered
busy
until
the
output
handshaking
begins.
Thus, a
new
trigger
will
indicate
a
measurement and
the
new
reading
will
replace
the old reading.
The
old reading
is
lost
and
there
is
no
SRQ
condition.
b.
Once
the Hrst character
of
measurement
data has
been
handshaken
out, the buffer
is
considered
busy
un-
til
one of
the following occurs:
1.
The
balance of the reading
is
handshaken
out.
2.
"Device"
or "Selected Device"
clear
is
given.
3.
The 34SSA
power
is
interrupted,
triggering
white
the
buffer
is
busy
will
lose
the
new
reading
and
cause
a
"Trigger
too
Fast"
SRQ
condition.
c.
When
triggering
and
taking
measurements
in
a
loop,
sufficient
time
must be
allowed
for the
345SA
to
perform
the entire
A-To-D
measurement
cycle
and
buf-
fer
data
to
become
available
after
the
first
reading.
The
"Wait"
statements
in
many
9800
series
calculators
are
convenient
methods
to avoid outputting the previous
buffer contents.
This condition
shows up
as
being
"One
reading
behind"
in
your measurement
sequence.
d. If
you
know
the
output
buffer
is
not busy, but
don't
know
whether
it
is
full
or
not,
sending a
"device"
or
selected
device"
clear
followed
by reprogramming
the desired conditions
is
a
safe
way
to clear
the
output
buffer.
3-14.
Bail
Out MessagB.
3-15. Abort.
The Abort
message
unconditionally
ter-
minates
all
Bus communications and
returns
control to
the
system
controller.
Only
the
system
controller
can
send
the
Abort
message. Refer
to
the
Operating
Manual
of
the controller
being used
for
instruaions
on
sending
the
Abort
Message.
3'BB.
Instrumont
Mtaauroffloiit
Timoi (Remots
Control).
3-87. In the
Remote
Operating
mode,
the
34SSA
takes a
certain
amount
of time
to
respond
to
a trigger
message.
The
overall
time
depends on
the range, function,
and
particular controller used.
This time
may
also
vary
from
instrument
to
instrument. Table
3-6 gives the
typical
measurement
times, using the
HP-IB. These
times are
not
part
of
the
operating
specifications
of
the
instru-
.'•l.l
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