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S E r n O N
4
GPIB Interfnce
GPIB
Primary
Address
The
GPIB
address of the Model
3910 is
set as follows:
On the front panel press the DISPLAY SELECT button so
that the red indicator light
is
on next to
GPIB
on the upper
left of the display. Then move the cursor by using the cur-
sor arrow keys so that the cursor is now in the
GPIB
dis-
play. Set the
GPIB
address by rotating the
MODIFY
knob
UP (clockwise) to inaease the value and
DOWN
(counter-clockwise) to decrease the value. Set values are
stored in battery backed-up memory when the power
is
turned off.
Delimiter
The Model 3910 recognizes
<CR>, <LF>,
or cEOb in any
combination
as
a delimiter for receiving code
strings
in
the listener mode.
The delimiter used when sending a response in
the
talker
mode is set from the front panel with the GPIB key. Only
cCR> or
<CR><LF>
can be selected as an output delim-
iter, and EOI
is
sent simultaneously.
Response to Interface Messages
Table 4 4 summarizes Model
3910
responses to interface
messages.
Table
4-4.
Response to Interface Messages
Program
Codes
IFC
DCL
and
SDC
LLO
GTI,
Program codes used for the various settings of
the
Model
3910 are temporarily stored in the input buffer
of the ma-
chine. When a delimiter
is
received, they are interpreted
and executed in the order received. The input buffer can
store up to
14
characters
(14
bytes). Note that space, tab,
and semicolons are not stored
in the
input buffer.
Initializes GPIB interface.
Releases specified listener and talker modes.
Clears
GPIB
input/output buffer.
Clears error status.
Releases SRQ transmission and resets SRQ
causes ( u n i t ' s operating modes do not
change).
Disables front panel
(LOCAL)
key.
Goes into local mode (front panel program-
ming enabled).
When more than 14 program code characters are re-
ceived, the input buffer overflows. When an overflow
oc-
curs, the input buffer
is
cleared, and program codes
stored in the buffer
are
not executed.
In addition, the input buffer
is
cleared, and subsequent
program codes are not executed when an illegal header
or parameter
is
found during the interpretation of a pro-
gram code.
When interpretation and execution are completed, the in-
put buffer
is
cleared, and the unit is ready to receive the
next program code.
As shown in Figure 4-4, program codes consists of
a
header and a parameter. More than one program code
can be sent at a time, up to a maximum of 14 characters.
Multiple program codes can be separated by a space or
semicolon
( ; )
to improve readability.
There
are
two general types of program codes:
parame-
ter-setting messages and inquiry messages. Parameter-
setting messages are used for setting parameters or for
sending operating instructions. Inquiry messages are
used for requesting state and parameter setting informa-
tion from the instrument.
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