Arrangement for the retention of data in programmable controllers

摘要

For the retention of data in programmable controllers, which are equipped with central processing units (200) and volatile memories (100), during time intervals when the voltage from the power supply network (4) has failed it is proposed to superimpose on the power supply network (4) a redundant, battery-backed (battery-maintained) DC voltage network (5) having at least n = 2 DC voltages (51 to 5n). A separate back-up battery (buffer battery) (401, 402) is assigned to each DC voltage (51 to 5n). Each module (assembly) (10, 20) having a volatile memory (100) and a central processing unit (200) is equipped with a connection module (interface module) (300), in which the operating voltage (350) for the volatile memory (100) is derived from the connected DC voltages (4, 51 to 5n) and in which means are provided for supervising (monitoring) the presence of the DC voltages (4, 51 to 5n), the status (360) of which is transmitted (relayed) to the central processing unit (200). <IMAGE>