Error preventing incremental measuring system

An incremental measuring system for lengths or angles, comprising a divided scale and a plurality of scanning elements, every scanning element delivering a signal changing between two binary values upon motion of the divided scale relatively to the scanning elements, the arrangement being such that some combinations of binary values of the various signals from the scanning elements do not occur in the case of faultless operation of all scanning elements (in the following called forbidden combinations contrary to permitted combinations), further comprising a logical network fed by the signals from the scanning elements, the logical network producing a binary output signal which is equal to a predetermined one of the signals from the scanning elements as long as a permitted combination of binary values is fed to the logical network, and which binary output signal is different from the said predetermined one of the signals from the scanning elements as long as a forbidden combination of binary values is fed to the logical network, further comprising at least two counters one of them being fed by the output signal of the logical network and an other of them being fed directly by the said predetermined one of the signals from the scanning elements, and further comprising a comparison circuit having a plurality of comparators for comparing the respective individual positions of the said counters.