Section
III
Mode! 3455A
Input
to
345SA:
-143.5
volts DC
Output Data Message:
-1.435000
E -t- 02 CR
LF
The 3455A
will
output a measurement data
message
when addressed
to
“talk**. The syntax for addressing
the 3455A is dependent upon the controller being used.
Refer
to the Operating Manual of your
controller for in-
structions.
NOTE
An
overload measuremeru
is
indicated
by
an
E
¥
10 exponent in (he HP-IB
measurement
data. The
large
exponent is
(he
key.
Also, note that the LF character
(concurrent
with
EOl)
is
the
last character in the data
message and must be handshook
from
the
34SSA to complete (he measurement
transfer.
3-69.
Davies ContrgI Messages.
3-70. Device control messages are issued by the system
controller to manage instruments on
the bus. These
messages are
controller dependent.
For
specific infor-
mation as to
syntax and procedures to transmit the con-
trol messages,
refer
to
the Operating Manual of the con-
troller being used.
3-71.
The following paragraphs describe the 3455A
response to the
various
control messages.
3-72.
Trigger Meessge. The trigger message causes the
3455A to initiate a measurement cycle. The 3455A must
be addressed to “listen” in order to recognize the
trigger
message. The measurement results of the 3455A depend
upon the control settings (FUNCTION, RANGE, etc.)
at the time the trigger message is
received.
3-73.
Clear Masuga. Upon receiving the clear message,
the 3455A sets the front panel controls to their
“turn-
on” state.
The turn-on state is as follows:
FUNCTION DC
VOLTS
RANGE AUTO
TRIGGER INTERNAL
MATH OFF
AUTO CAL
ON
HIGH RESOLUTION OFF
DATA READY RQS OFF
BINARY PROGRAM
OFF
The 345SA
will
respond to the
device
clear
message
whether
addressed to “listen” or not. To respond to the
selected
device
clear message, the 3455A must be
ad-
dressed
to
listen.
3-74. Remote Message. The 3455A will
go
to Remote
(Bus)
control when the remote message, in conjunction
with its “listen” address, is
received.
Remote
operation
is indicated
when
the
REMOTE indicator, located
above
the
display, is
lit.
During remote operation, the
front panel controls cannot be operated
manually.
3-7S. Local Message. The local message returns the
3455A to LOCAL (manual)
control. The 3455A can
also be
returned
to
local control by pressing the front
panel LOCAL button. Some circuits of the instrument
may also be in local operation
when
a local message is
send to another instrument on the HP-IB.
7-7B
Local Leckoet Message. The local lockout message
disables the front panel LOCAL
control.
In the
local
lockout mode, the 345SA
cannot
be
returned to local
operation from the front panel.
3-77. Clear Lockout and Local Message. The 3455A
will
set
the front
panel
to
LOCAL (manual) operation and
enable the LOCAL control upon
receiving
the clear
lockout and local message.
3-78. Intemipt end Device Status Massages.
3-79.
The interrupt and
device
status messages permit
the 3455A to notify the
controller when an error in pro-
gramming
information or measurement output data oc-
curs. The 3455A
also
uses these
messages
to
notify the
controller
when
measurement data is
available if the
DATA READY REQUEST
feature is programmed.
3
80. Rsquira Service Message. The
following
conditions
will cause the 345SA to output a Require
Service (SRQ)
message.
a. Data Ready.
If the DATA READY REQUEST
feature is
programmed, the 3455A
will
output an SRQ
message upon
completing the required measurement.
b.
Syntax Error. The 3455A
will
output
an
SRQ
message if a
program code other than those listed in
Table
3-4
is received. For example, the program
code
“F7”
would cause a syntax error since the
FUNCTION
program set only
contains codes FI through F6.
c.
BINARY PROGRAM
Error.
The
3455A will out-
put an SRQ message if a
BINARY PROGRAM code
other than those
listed
in
Table
3-5
is
received.
d. Trigger Too Fast. An SRQ message
will
be
output
if the 34S5A is
triggered while outputting data to the
bus. This
condition most commonly occurs if the 3455A
is programmed to
INTERNAL TRIGGER during bus
operation. The
front panel SRQ indicator is lit
when
the
3455A
requires service. The Require
Service message
can be cleared by
serial polling the 3455A or by clearing
the
3455A.
-'•12
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