The article concentrates on the review and the solving of the problems of the diagnostics support of non-contact track coordinate dimensioning system (SBPP) of subway trains, based on RFID technologies. In the text there is a detailed discussion of the problems of assignment and of SBPP structure, but the main attention is paid to the solution of the problem of reader-antenna path control. The reason for the growing interest specifically to this subject were few cases of missing of station radio-frequency tags during the system operation. To explain that the authors have developed a hypothesis that interprets the missing of tags by the processes of increasing the intermediate resistance in connectors of reader-antenna path and of inflowing of the moisture into detachable connections during carriage washing. The article proposes, using axiomatic-deductive reasoning method, a method for controlling a stationary mode of SBPP equipment’s RFID path, that allows to ensure the efficiency of the latter during the process of planned maintenance inspection before departure of trains from the railway depot to the line. To enable the possibility of further implementation of the method the necessary experimental research have been carried out, that were aimed at studying of the process of attenuation increasing in the reader-antenna path. The article provides the results obtained by processing the statistical data. The basic provisions of the proposed method are verified by using correlation analysis. Based on these results the article gives recommendations on the application of the method of the RFDI path state control of the RFID. The practical value of the proposed solution, that allows to increase the system operational reliability by minimizing the possibility of putting into operation the train line with inoperative RFID hardware, is also noted.