Safe test arrangement

In order to provide a flexible test arrangement for performing measurements on a test object, according to the invention a plurality (n) of safety components (11,12,13) each having a safety module (M) which can be set to active or inactive mode and a ready state (r) which can be set to active or inactive mode are provided in a ring-like test arrangement, in which each of the safety components (11, 12, 13) carries out a number of function tests (T) cyclically, one of said function tests (T) involving testing cyclical error-free reception of a data packet (DP). One of the safety components (1, 11, 12, 13) is selected as a bus master (BM) which cyclically transmits a bus checking signal (B) in a data packet (DP1) to the next safety component (11, 12, 13) provided in the transmission direction, said bus checking signal (B) being relayed by each of the safety components (11, 12, 13) in a data packet (DP2, DP3), and, when said bus checking signal (B) is received in a data packet (DP3). the bus master (BM) identifies a closed ring-like test arrangement.