Method of checking first pilot relay and second pilot relay of cyclic code encoder for railway interlocking installation and cyclic code encoder for making the method

The method for checking the first check relay (X) and second check relay (Y) of the coding unit (C) according to this invention consists in that, the check circuit (CCC) of the cyclical codes periodically, after the repeating control time (TSC) elapses, looks for an intersection of the common state, when the cyclical codes (CC1, CC2, CC3, CC4), generated simultaneously in both the first branch (B1) and in the second branch (B2) all have zero voltage (UO) in the first branch (B1) and, at the same time, in the second branch (B2). Immediately after detecting this instant the cyclical code check circuit (CCC) initialises an impulse to the diagnostic circuit (DC) for the period of the testing time (TT), to interrupt, through the diagnostic switches (d1, d2), the driving circuits of the check relays (X, Y), whose armatures are released for a short period after the testing time (TT). After the testing time (TT) elapses, the diagnostic circuit (DC) connects, through the diagnostic switches (d1, d2), the driving circuits of the check relays (X, Y), whose armatures attract, if they have a failure-free state. In this case the result switch (S) of the output switching circuit (OS) is not dropped, because its armature is belatedly released after the time (TD) of delay, during the interruption of its excitation, where the time (TD) of delay is longer than the testing time (TT), thus during a failure-free state during the test there is no interruption to the distribution of the cyclical codes (CC1, CC2, CC3, CC4) over the output switching circuit (OS) and return conductor (RCC) to the interlocking system equipment (IS), under the condition, that there has been no long-term jamming of the contacts of either the first check relay (X) or the second check relay (Y), in the operating or rest position. Because, in this case, this would lead to the constant drop of the relevant faulty relay, i.e. either of the first check relay (X) or second check relay (Y), due to the interruption of power to the first branch (B1) or the second branch (B2) as a result of the incompatible state of the connection of the second contact (x2), third contact (x3) of the first check relay (X) or the second contact (y2) and third contact (y3) of the second check relay (Y) which, in this case, causes the droppage of the result switch (S) and the function of the coding unit (C) is interrupted, until the arrival of the operator and until the elimination of the fault and until the initialisation of the ac