The determination of the average number of completed requestsfor a diagnostic test of measuring controllers in health monitoring systemsThe article considers the problem of the providing of the testing the most unreliable level of modern systems of external technical diagnosis and monitoring of railway automation and remote control devices - the level of diagnostic information collection by measuring controllers. It is noted that the measuring controllers of railway automation monitoring systems self-diagnosis procedure is initiated by the hub of diagnostic information, to which the measurement controllers are connected. The timeliness of the identifi cation of disturbances in the measuring controllers operation depends on the diagnosis period, the time of fi ling the test, and on the set of test combinations. It is proposed to consider the issue of the sensors of measuring controllers testing as a task of the queuing process in the mass service system. All applications are divided into two categories according to priorities: the fi rst category includes the working signals from the objects of diagnosis (high-priority applications), and the second category includes the code vectors of the diagnostic test (low-priority applications). Applications from the objects of diagnosis have absolute priority over the test load. In this regard, the article developed the approach to the determination of the average number of requests of the diagnostic test with the absolute priority and also with the relative priority. The practical side of the result is the ability to select the most effective time intervals for the test impact on the measuring controller sensors in the monitoring system and the selection of the test procedure time.