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SECTION 4
GPIB
Interface
+
Front Panel Display
K,u, etc.
.1234
OF, UF, OU
Blank; measured
value not displayed
GMB Output
E+03, E-06, etc.
0.1234
Numbers like
"99999.E+06"
Numeric like "77777."
4.6
MEASUREMENTS
OVER GPIB
Measurement
over the GPIB is basically the same as mak-
ing measurements
from the front panel. Before using the
GPIB, make sure front panel operation (Section 3) is un-
derstood.
4.6.1
Preparation
1. Input/output
Connections
-
Connect a test fixture
or test leads to the instrument,
and perform zero cor-
rection.
2. Initial GPIB Settings:
l
Interface clear (IFC) -Initialize
the GPIB system
by sending the interface clear command from the
controller.
l
Remote enable (REN) -
Send the REN message
from the controller
to enable the instrument
to
respond to GPIB commands. The REN command
must be true (REN line = Low). To control the in-
strument
over the GPIB, REN must be main-
tained true unless some front panel operation is
needed.
l
Device clear (DCL, SDC) -
Initialize
the GPIB
system of the instrument
by sending
a device
clear command from the controller. The transmit
and receive buffers will be cleared, and any pre-
vious error will reset. SRQ will disable, and the
header for an inquiry message will disable.
4.6.2
Measurement
and
Reading of Data
This paragraphs
describes how to make a measurement
and send the reading (data) over the GPIB bus to the con-
troller.
Set Measurement
Conditions
Example:
"FR lE3;LV 1"
FR lE3:
Frequency = 1kHz
LV 1:
Measuring
signal level = 1Vrms (output
open)
Set Display
Example:
"DA 2; DB l;CK 1"
DA 2:
C is displayed on m
DISPLAY (electro-
static capacity)
DBl:
CKl:
D is displayed on m
DISPLAY (Dissi-
pation)
Equivalent
circuit (CKT) is series (SER).
Perform Measurement
Send the following command string to select the manual
trigger mode, and make a single measurement:
"TG"
TG:
Applies a trigger and performs one meas-
urement. The GET command can be used
instead.
Read Data
Once the measurement
has been made, the reading (data)
is sent to the computer by programming
the instrument
to talk.
SRQ can be used to ensure that the measurement
is com-
pleted before sending the reading by programming
the
instrument
to talk. To enable SRQ, send the following
command before making the measurement:
"RQ 1"
When an SRQ occurs, serial poll the instrument
to con-
firm that the RQS bit is set, and then program it to talk.
Another way to verify the completion of a measurement
is to read the status byte using the "?ST" inquiry message
and wait until the BUSY bit (Bit 4) is reset.
4-18
+
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