Patent ID: 8148997

Claim:
A method for monitoring whether the switching threshold (SwU, SwI, U Smin , U ref 5 ) of a switching transducer (K, K 5 , OK, W, ZK), especially of a comparator (K, K 5 , ZK), lies within a predefined tolerance range or not, whereby the switching transducer (K, K 5 , OK, W, ZK) has a signal input (KE 1 , OKE, ZKE 1 ) at which an input signal is present, as well as a switching output (KA, OKA, ZKA) and, via the switching output (KA, OKA, ZKA), it emits a switching output signal (S 3 , S 3 ′, S 3 ″, S 5 , ZS 3 ) that takes on a first value (W 1 , W 3 , W 5 ) if the input signal is greater than the switching threshold (SwU, SwI, U Smin , U ref 5 ), and otherwise, it takes on a second value (W 2 , W 4 , W 6 ), wherein a) as the input signal, a modulator signal (MS, MS′, MS″, ZMS, MS 5 ) generated by a modulator (MD, MD′, MD″, MD 5 ) is used, said modulator signal changing continuously or cyclically between an output value (U 1 , I 1 , U 3 , U 5 ) that specifies the upper limit (U 1 , I 1 , U 3 , U 5 ) of the tolerance range and a test value (U 2 , I 2 , U 4 , U 6 ) that is smaller than the output value (U 1 , I 1 , U 3 , U 5 ) and that specifies the lower limit (U 2 , I 2 , U 4 , U 6 ) of the tolerance range, so that the switching output signal (S 3 , S 3 ′, S 3 ″, ZS 3 ) then pulsates synchronously with the modulator signal (MS, MS′, ZMS, MS 5 ) between the first value (W 1 , W 3 , W 5 ) and the second value (W 2 , W 4 , W 6 ) when the switching threshold (SwU, SwI, U Smin , U ref 5 ) of the switching transducer (K, K 5 , OK, W, ZK) lies within the tolerance range, and otherwise, it does not pulsate, b) and the switching output signal (S 3 , S 3 ′, S 3 ″, S 5 , ZS 3 ) is monitored for pulsation by means of an evaluation unit (A, AWS, MA, ZA), and an alarm signal (AS, ZAS) is triggered if the switching output signal (S 3 , S 3 ′, S 3 ″, S 5 , ZS 3 ) does not pulsate for at least a predefined test time period (dt, dT, dt′).