Switching matrix, generator and measurement units should be validated on a regular base by using external measurement devices. Therefore, they will be adapted at freely definable test points.


Diagnostics are qualitative measurements; that means they can only prove or disprove the correct functioning.

Diagnostics of the generator
Diagnostics of the generator is often the start point for comprehensive diagnostics of the test system. It is programmed to specific voltages or currents and the values validated by an external measurement unit (CMU*, VMU*).

Diagnostics of the measurement units
When the accuracy of the generator has been proved, the internal measurement units can be validated. In case the detected values for current and voltage match the programmed values at the generator, the accuracy of the measurement units can be confirmed.

Continuity test of the switching matrix
A and B switches at one test point are closed simultaneously. The VMU measures the voltage drop at the relay contacts (respectively CMOS switches or transistors) and determines the resistance. Is it higher than the threshold value (e.g. 1 Ohm), it's rated as a failure (FAIL). This test step is being repeated for all test points.

Leakage current diagnostics of the switching matrix
All A switches on a test point module are closed while all B switches stay open. The CMU* measures the fault current and determines the resistance. In case it is lower than the threshold value (e.g. 1 Ohm) it's rated as a failure (FAIL). Afterwards the same test is repeated with opened A switches and closed B switches.

To run a complete calibration the entire diagnostics needs to be performed after a defined process und logged according to specific, national standards.

A regular validation could be part of specific industry standards and in case of a certification mandatory to the manufacturer.

*CMU = Current Measurement Unit
*VMU = Voltage Measurement Unit