Method for operating a bus system; the bus system comprising at least two bus lines (1, 3) formed as respective loops, a plurality of switching elements (5 1 to 5 n) connected in series so as to divide one of the bus lines in a plurality of sections, a central control unit connected with the ends of the bus lines (1, 3), and a plurality of bus devices (9 1 to 9 m) connected in parallel between the two bus lines (1, 3) and distributed along the bus lines (1, 3) so that a bus device (9 y) is interposed between two consecutive switching elements (5 x, 5 x+1); the method comprising the steps: (a) applying a supply voltage to both ends of the bus lines (1, 3) starting from terminals (A, B) of the central processing unit; (b) closing the switching elements (5 1, 5 n) upon reception of the supply voltage, so as to connect the subsequent respective sections of the bus from both ends; (c) monitoring the bus lines (1, 3) in order to detect a first short circuit; if no first short circuit is detected repeating the steps (a), (b) and (c) until all switching elements (5 1, 5 2, 5 3, 5 4,..5 n) are closed or until a first short circuit is detected; if a first short circuit is detected, (d) opening the two switching elements (5 x, 5 (m-x)) closed immediately before detecting the first short circuit, (e) closing again one of the switching elements (5 x) opened in step (d); (f) monitoring the bus lines (1, 3) in order to detect a second short circuit; if a second short circuit is detected, (g) opening the switching element (5 x) closed immediately before detecting the second short circuit and keeping this switching element (5 x) open, and (h) closing again the other switching element (5 (m-x)) opened in step (d). the bus system comprising at least two bus lines (1, 3) formed as respective loops, a plurality of switching elements (5 1 to 5 n) connected in series so as to divide one of the bus lines in a plurality of sections, a central control unit connected with the ends of the bus lines (1, 3), and a plurality of bus devices (9 1 to 9 m) connected in parallel between the two bus lines (1, 3) and distributed along the bus lines (1, 3) so that a bus device (9 y) is interposed between two consecutive switching elements (5 x, 5 x+1); the method comprising the steps: (a) applying a supply voltage to both ends of the bus lines (1, 3) starting from terminals (A, B) of the central processing unit; (b) closing the switching elements (5 1, 5 n) upon reception of the supply voltage, so as to connect the subsequent respective sections of the bus from both ends; (c) monitoring the bus lines (1, 3) in order to detect a first short circuit; if no first short circuit is detected repeating the steps (a), (b) and (c) until all switching elements (5 1, 5 2, 5 3, 5 4,..5 n) are closed or until a first short circuit is detected; if a first short circuit is detected, (d) opening the two switching elements (5 x, 5 (m-x)) closed immediately before detecting the first short circuit, (e) closing again one of the switching elements (5 x) opened in step (d); (f) monitoring the bus lines (1, 3) in order to detect a second short circuit; if a second short circuit is detected, (g) opening the switching element (5 x) closed immediately before detecting the second short circuit and keeping this switching element (5 x) open, and (h) closing again the other switching element (5 (m-x)) opened in step (d). (a) applying a supply voltage to both ends of the bus lines (1, 3) starting from terminals (A, B) of the central processing unit; (b) closing the switching elements (5 1, 5 n) upon reception of the supply voltage, so as to connect the subsequent respective sections of the bus from both ends; (c) monitoring the bus lines (1, 3) in order to detect a first short circuit; if no first short circuit is detected repeating the steps (a), (b) and (c) until all switching elements (5 1, 5 2, 5 3, 5 4,..5 n) are closed or until a first short circuit is detected; if a first short circuit is detected, (d) opening the two switching elements (5 x, 5 (m-x)) closed immediately before detecting the first short circuit, (e) closing again one of the switching elements (5 x) opened in step (d); (f) monitoring the bus lines (1, 3) in order to detect a second short circuit; if a second short circuit is detected, (g) opening the switching element (5 x) closed immediately before detecting the second short circuit and keeping this switching element (5 x) open, and (h) closing again the other switching element (5 (m-x)) opened in step (d).