Device for monitoring machines

摘要

In order to protect personnel and for safe operation of machines and mechanical installations which are used especially in underground mining and tunnel construction a safety circuit is used which, in the event of a defect, switches off running drives and prevents stationary drives being switched on. For this purpose, active stopping stations which are allocated to the drives are required as well as a central apparatus and a terminal stopping unit. The central apparatus stopping unit and the terminal stopping unit are in each case equipped with a parallel/series converter and with a series/parallel converter, as well as with an intermediately connected evaluator. In consequence it is possible to convert and to evaluate the serial data word which is in each case sent from the other apparatus via the safety circuit and, if said data word is free of errors, to send back another serial data word to the other apparatus. The evaluators of the active stopping stations, which evaluators are coupled to the safety circuit, enable the associated relay only as long as the data flow on the safety circuit is uninterrupted in both directions. <IMAGE>