The paper describes a measuring system implemented on the rail welding machine PRSM-4 No. 083. The measuring system monitors and controls all parameters of rail welding procedure in real time. The paper gives an overview of the measurement of all relevant variables, control of the duration of individual welding phases and of the basic options of the command software. The paper describes the most important parts of the measuring block and presents the results of the system exploitation on over 10,000 completed welds on territories of Serbia, Montenegro and Bosnia and Herzegovina during a period of about two years.