Digital electric length or angle measuring device with a circuit for error control

摘要

In such a position-measuring device, a first binary signal (B1a) from a sensing unit (A) is fed via a first transmission line (L1) and a second binary signal (B2a) via a second transmission line (L2) of a transmission path (ST) to an evaluation unit (AW). For the purpose of detecting errors in the transmission of the two binary signals (B1a, B2a), a first redundant binary signal (RB1a) is generated upstream of the transmission path (ST) from the two binary signals (B1a, B2a) by means of a first exclusive OR gate (AG1) and a second redundant binary signal (RB2) is generated downstream of the transmission path (ST) from the two transmitted binary signals (B1b, B2b) by means of a second exclusive OR gate (AG2). The first redundant binary signal (RB1b) and the second redundant binary signal (RB2) transmitted on a redundant transmission line (LR) of the transmission path (ST) are fed to a comparator (V) in the evaluation unit (AW) to generate an error detection signal (FES) to characterise the equality or inequality between the two redundant binary signals (RB1b, RB2) (Fig. 1). IMAGE