Table of Contents
Advertisement
IEEE-488 PROGRAMMING
Step 4: Program Model 194 Operating
Modes
You can program instrument
operating modes by sending
the appropriate command, which is made up of an ASCII
letter representing
the command, followed by one or two
numeric parameters separated by commas for the com-
mand o$ion.
Table 4-l summarizes
the most often used
Model 194 commands.
A number of commands can be grouped together in one
string, if desired. Also, you must terminate the command
or command string with the X character in order for the
instrument
to execute the commands
in question.
If you are using the programming
examples from Step 3
above, simply type in the command string when prompted
to do so. Some example strings are given below.
ClX: select channel I.
FOROX: program waveform function,
autoranging.
FlN0,12OOX: program average function,
1200 samples per
measurement.
IlR3F7X:
program
AC coupling,
32V range,
integral
function.
NOTE
Many controllers,
including
the HI-'-85 and IBM-
PC, use commas to delimit their BASIC INPUT
statements. When using the above programs, use
different delimiter such as / or <space > in dual-
parameter commands. For example, use NOilOOX
instead of NO,lOOX.
Step 5: Get Readings from the Model 194
Usually, you will want to obtain one or more readings from
the Model 194. In the example programs above, a single
reading is requested and displayed after each command.
In other cases, you may wish to program the instrument
configuration
at the beginning
of your program, and then
obtain a whole series of measurements.
The basic reading string that the Model 194 sends over the
bus is in ASCII characters of the form:
NDCV-1.2345E+O, CHI
where: N indicates a normal reading (0 would indicate
an overflow),
DCV shows the math function in effect (in this LISC',
waveform),
-1.2345 is the mantissa of the reading data,
E+O represents the exponent.
011 is the channel number (1 or 2)
Note that a variety of both ASCII and binary data formats
are available, as discussed in paragraph 4.9.
4.3 BUS CONNECTIONS
The Model 194 is intended to bc connected tc> the IEL;li-4#
bus through a cable equipped with standard II+LlHH
cow
nectars, an example of which is shown in Figure 4-2. The
connector is designed to be stacked to allwv a number of
parallel connections
at one instrument.
'Two screws are
located on each connector to ensure that connections
re-
main secure. Current
standards call for metric threads,
which arc identified
with dark colored screws. Earlier vw
sions had different screws, which wcrc silver colored. Do
not attempt to use these type of connectors on the Model
194, which is designed for metric threads.
Figure 4-2. IEEE-488 Connector
A typical connecting scheme for a multiple-instrument
test
setup is shown in Figure 4-3. Although
any number of ax)-
nectars can be stacked on one instrument,
it is recom-
mended that you stack no more than three connectors on
any one unit to avoid possible mechanical
damage.
4-3
Advertisement
Table of Contents
