Measx - Keithley 4200A-SCS Reference Manual

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Section 13: LPT library function reference

measX

This command allows the measurement of voltage, current, or time.

int meast(int instr_id, double *result);

int measi(int instr_id, double *result);

int measv(int instr_id, double *result);

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 measX 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 measX and intgX is the integration time. For measX, the integration

time is fixed at 0.01 PLC. For intgX, 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 rangeX command directly affects the operation of the measX command. The use of the rangeX

command prevents the instrument addressed from automatically changing ranges when the measX

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 rangeX command must be in the test sequence before the associated measX 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

The instrument identification code

The variable assigned to the result of the measurement

Compliance limits

Model 4200A-SCS Parameter Analyzer Reference Manual

(on page 3-3) for details.

4200A-901-01 Rev. C / February 2017