HP 54501A - Page 73

TRG
•
trigger.
Indicates whether
a
trigger
has
been
received.
LTF
-
limit
test
failure.
Indicates
whether
a
limit
test failure
has
occurred.
Key Features
A
few
of
the
most
important
features
of Status
Reporting
are
shown
below.
Operation
Complete.
The
IEEE
488.2
structure
provides
one
technique
which
can
be
used to
find
out
if
any
operation
is
finished.
The
*OPC
command,
when
sent
to
the
instrument
after
the
operation
of
interest,
will
set the
OPC
bit
in
the
Standard
Event
Status
Register.
If the OPC
bit
and
the
RQS
bit
have
been
enabled,
a
service
request
will
be
generated.
OUTPUT
707;"*SRE
32;
*ESE
1"
!enables
an
OPC
service
request
OUTPUT
707;":DIG
CHAN1;
*OPC" iinitiates
data
acquisition,
and
!will
generate
a
SRQ
when
the
!
acquisition
is
complete
The
Trigger
Bit.
The
TRG
bit
indicates
if
the
device
has
received
a
trigger.
The
TRG
event
register
will
stay
set
after
receiving
a trigger
until
it
is
cleared
by
reading
it
or
using
the
*CLS
command.
If
your
application
needs
to
detect
multiple
triggers,
the TRG
event
register
must
be
cleared
after
each
one.
If
you
are
using
the
Service
Request
to
interrupt a
program or
controller
operation
when
the
trigger
bit
is
set,
then
you must
clear
the
event
register
after each
time
it
has
been
set.
OUTPUT
707;"*SRE
I"!
enables
a
trigger
service
request.
!
the
next
trigger
will
generate
an
SRQ.
OUTPUT
707;":TER?"!
queries
the TRG
event
register,
thus
ENTER
707;A$!
clearing
it.
!
the
next
trigger
can
now
generate an
!SRQ
Status
Byte.
If
the
device
is
requesting
service
(RQS set),
and
the
controller
serial
polls
the
device,
the
RQS bit
is
cleared.
The
MSS
bit
(read
with
*STB?) will
not
be
cleared
by
reading it.
The
status
byte
is
not
cleared when
read,
except
for
the
RQS
bit.
HP
54501A
Message
Communication
and
System Functions
Programming
3-31