A measured value transmitting device for serially transmitting data in accordance with the SSI method, includes a slave providing the data bits of a measured value detected by a sensor for serial bit-by-bit transmission to a master. The master requests a measured value from the slave with a clock burst having multiple clock cycles matching the number of data bits to be transmitted. In a first device, the clock cycles have a specified duty cycle corresponding to the ratio of the pulse duration to the period duration of one clock cycle, and the master contains a comparator. The master reads the clock bursts outputted on the clock line and checks the duty cycle in the comparator to determine whether an upper and/or lower threshold has been exceeded. In a second device a corresponding check of the duty cycle is carried out in the slave.