Data Messages; Device Control Messages; Interrupt And Device Status Messages 0.5. C0-05. 00S - HP 3455A Operating And Service Manual

Section III
Input to 3455A: -143.5 volts DC
Output Data Message: - 1.435000 E + 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 measurement is indicated by an
E + 10 exponent in the HP-IB measurement
data. The large exponent is the key.
Also, note that the LF character (concurrent
with EOD) is the last character in the data
message and must be handshook from the
3455A to complete the measurement
transfer.
3-69. Device Control 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 Message. 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. Claar Message. 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 ....... ee cece eee eee eee AUTO
TRIGGER ....... .... INTERNAL
MATH a nicaing) inet so ean ge eo en OFF
AUTO CAL. ... onesie ap hisiend paar ee ON
HIGH RESOLUTION .... OFF
DATA READY RQS ..... igne OFE
BINARY PROGRAM ............. OFF
The 3455A 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.
3-12
Model 3455A
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.
3-75. 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.
' 7-76 Local Lockout Message. The local lockout message
disables the front panel LOCAL control. In the local
lockout mode, the 3455A cannot be returned to local
operation from the front panel.
3-77. Clear Lockout and Loca! 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. Interrupt and Device Status Messages.
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. Require Service Message. The following conditions
will cause the 3455A to output a Require Service (SRQ)
message. ae;
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 F1 through F6.
ce, 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 3455A 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.