Section 13: LPT library function reference
Model 4200A-SCS Parameter Analyzer Reference Manual
13-78
4200A-901-01 Rev. C / February 2017
measX
This command allows the measurement of voltage, current, or time.
Usage
int meast(int
instr_id
, double *
result
);
int measi(int
instr_id
, double *
result
);
int measv(int
instr_id
, double *
result
);
instr_id
The instrument identification code
result
The variable assigned to the result of the measurement
Details
For a measurement conversion, the signal is sampled for a specific period of time. This sampling time
for measurement is called the integration time. For the
meas
X
command, the integration time is fixed
at 0.01 PLC. For 60 Hz line power, 0.01 PLC = 166.67 µs (0.01 PLC/60 Hz). For 50 Hz line power,
0.01 PLC = 200 µs (0.01 PLC/50 Hz).
The only difference between
meas
X
and
intg
X
is the integration time. For
meas
X
, the integration
time is fixed at 0.01 PLC. For
intg
X
, the default integration time is 1 PLC, but can set to any PLC
value between 0.01 and 10.0.
After the command is called, all relay matrix connections remain closed, and the sources continue to
generate voltage or current. For this reason, two or more measurements can be made in sequence.
The
range
X
command directly affects the operation of the
meas
X
command. The use of the
range
X
command prevents the instrument addressed from automatically changing ranges when the
meas
X
command is called. This can result in an overrange condition such that would occur when measuring
10 V on a 4.0 V range. An overrange condition returns the value 1.0E+22 as the result of the
measurement.
If used, the
range
X
command must be in the test sequence before the associated
meas
X
command.
All measurements except the
meast
command invoke a timer snapshot measurement to be made by
all enabled timers. This timer snapshot can then be read with the
meast
command.
In general, measurement commands that return multiple results are more efficient than performing
multiple measurement commands.
Compliance limits
: A compliance limit setting goes into effect when the SMU is on a measure range
that can accommodate the limit value. For manual ranging, the
rangeX
command is used to select
the range. For autoranging, the
measi
or
measv
command will trigger a needed range change before
the measurement is performed. See
(on page 3-3) for details.
