The measurement mode is an operational mode of the measurement hardware. Generally it can be operated in the measurement mode if measurement units (e.g. CMU*, VMU*) are integrated into a test system.
With every test step, the measurement device provides the values of current and voltage at the test points and thus indirectly the value of the effective load resistance. This value is determined by applying Ohm's law. Just like at the comparator mode the UIG* operates either in the current-controlled or in the voltage-controlled mode. In addition, the respective other value is accurately measured and the exact load resistance calculated. The so determined value is compared to a programmed threshold value and the test step rated as either PASS or FAIL.
For example, during an open test, a programmable constant current is provided and the voltage drop at the unit under test (UUT) measured. In a short test, the generator supplies a constant voltage and the floating current is measured.
For a component test, here is the opportunity to program the frequency at some test systems from WEETECH (W 434, W 444, W 454 and W 454 HV / W 454 SHV). This way the combinations of resistor (R), inductance (L) and capacitance (C) can be measured (see RLC measurement).
Actually, this is not a measurement mode in true sense but via the comparison with known values (by a generator programmed current or voltage) the achievement of a target value can be determined qualitatively.
Measurement of external voltage
External voltages are voltages of external power supply units, interconnected with the unit under test during the test. Often they are mandatory when a functional test is running. The measurement of these voltages is executed by the VMU of the test system and can be necessary to ensure the complete test of the UUT.
*CMU = Current measurement unit
*VMU = Voltage measurement unit
*UIG = UI-generator