| 摘要 |
A data communication installation includes a central unit (C) and a desired number of terminal units (T). The units are in mutual communication via a two-wire network (N). A balanced voltage signal is used for the two-way signal transmission in one direction, and in the other direction a differentially detected current signal is used. The balanced voltage signal is generated by switching (via K1, K2) of the feed voltage (+U, -U) and is detected with the aid of a comparator circuit (D1), whereby transmission data (S1), which regulate the voltage signal, are obtained as received data (M1) on the output of the comparator circuit. The current signal is generated by current regulating means (K3) and is detected as voltage drop signals across two resistors (R1, R2). Fed-in transmission data (S2) control the current regulating means and, via the voltage drop signals fed to a comparator circuit (D2), give rise to received data (M2) on the output of the comparator circuit. |
