The present paper concerns a simulator’s scheme of cable links based on the equivalent circuit of RLC-chains on the lumped elements and controlling apparatus based on the programmed microcontroller to test the systems of signals transmission through the wired communication links. The information about the emulated cable’s type, its length and diameter of cable’s lead, presence of noise and its level, is inputted by means of a keyboard to a microcontroller, which, as per the inputted data, carries out commutation of cable net’s links and their elements in order to form the cable lines with necessary parameters. The simulator of cable lines emulates the parameters and characteristics of the symmetric copper communications links of different types, cable’s lead diameter and dimension of communications link. The simulator also sets the necessary relation of the signal/noise on the communications link output. It provides a value of variation of parameters influence degree of the equivalent circuit’s lumped elements on the frequency response changing of the emulated cable line. Taking into account an equivalent circuit’s lumped elements, the paper studies a degree of parameters variation influence upon changing the frequency response of the emulated cable line. As a result, we obtain the analytical and graphical functions of a cable line’s attenuation factor module sensitivity to the equivalent circuit parameters of lumped elements.