The voltage values used in an IV measurement often depend on the specific electronic components being tested. For example, to test a solar cell, voltage values in the range of -3 V - 3 V are sufficient, while for an LED this value is in the range of 0 V - 12 V. However, sometimes applying a voltage can change the electronic properties of a system under test. For example, the voltage applied to a diode changes the capacitive values of the diode. Therefore, the parameters of the tested system should not change the current-voltage values of the testing system during the test. In this study, a software-controlled current-voltage device was designed and built to overcome this problem. We interpreted the accuracy of this system by measuring the turn-on voltage of an OLED device we produced in the laboratory.