Heavy-duty trucks and self-propelled platforms are widely spread for the purpose of transportation of heavy and bulky loads. Power units of these vehicles consist of synchronous electric generators (alternators) driven by diesel engines. The generator supplies electricity to each motor-wheel of the vehicle and to all its systems. Alternators are also used in cars' and trucks' electric systems to supply their electric and electronic devices (e.g., headlights, safety systems, etc.). Substantial reserves of production and quality improvement of such alternators are hidden in their tests technique improvement. In this paper, the software is designed for mobile and stationary test stands of the alternators. The software was created using "LabVIEW" development system. It is designed to be used with "National Instruments®" hardware. By manually or automatically, the software allows receive: the no-load characteristic, the no-load loss characteristic, the short-circuit characteristic, the short-circuit loss characteristic, the V curves characteristic and the load angle characteristic. It also allows to determine static (right up to efficiency) and dynamic parameters during the tests. The software consists of six virtual instruments (VIs) based on specific algorithms which have been developed under the leadership of the author of this paper. They include special adaptive algorithm of sliding trigonometric interpolation which aim is to filter noise of the input signals and draw curves for steady-state and transient processes, and combined optimizing algorithm. That is needed for reliable determination of the dynamic parameters based on the results of the sudden short circuit test of the synchronous generator. Nonlinear parameters (time constants) are determined by using the alternating-variable descent method. Linear parameters (initial values of transient processes) are determined analytically at each step of nonlinear parameters optimization using earlier derived formulas. The software is considerably extended for stationary test stands, additionally based on "NI PXI" programmable logic controller and static thyristor exciter with micro-integrated system (e.g., "Simoreg DC Master"). In the first place, it is due to the extra VI, which allows to cut time of receiving machine's characteristic in automation mode. The VI has a stator voltage control loop with PID controller which provides significant forcing of the field with a desired value of the overshoot. The algorithm optimization for PID control is also included in the VI.The software for receiving characteristics and determination of static and dynamic synchronous machines' parameters was tested by using simulated and also real information. The program tests show that the error in determination of parameters will not exceed 5% for the noise level of 30% of the useful signal (stator winding voltage).Though the software was designed to be used with alternators, it also can be used at test stands for synchronous motors and condensers.