A dual-channel data processing system, for operating a safety device, comprising:
- a data input for receiving data to be processed and a data output for connection to the safety device;
- first and second microcomputers, each of said microcomputers including a plurality of input lines connected to said data input and a plurality of output lines and each of said microcomputers operable to process data received on its input lines and produce processed data on its output lines;
- first and second comparators each including an output, first inputs connected to the output lines of said first microcomputer and corresponding second inputs connected to said output lines of said second microcomputer, and each of said comparators operable to provide a first signal at its output in response to receiving equal data from said microcomputers and a second signal at its output in response to receiving unequal data from said microcomputers;
- first and second AND gates each including an output, a clock input for receiving clock pulses, and a signal input connected to said output of a respective comparator, said AND gates operable in response to clock pulses and said first signals to produce rectangular pulses at their respective output;
- first and second rectifiers, and first, second and third transformers each including a primary and a secondary;
- and
- first, second and third pulse amplifiers each including a voltage supply input, a pulse input and an output,
- said voltage supply input of said first pulse amplifier connected to a voltage supply, said output of said first pulse amplifier connected to said primary of said first transformer and said pulse input connected to said output of said first AND gate, said first pulse amplifier operable in response to the rectangular pulses to cause said first transformer to couple pulses to said secondary of said first transformer,
- said voltage supply input of said second pulse amplifier connected via said first rectifier to said secondary of said first transformer, said output of said second pulse amplifier connected to said primary of said second transformer and said pulse input of said second pulse amplifier connected to said output of said second AND gate, said second gate amplifier operable in response to the rectangular pulses and the operation of said first pulse amplifier to cause said second transformer to couple pulses to said secondary of said second transformer,
- said secondary of said third transformer connected to said data output, and
- said voltage supply input of said third pulse amplifier connected via said second rectifier to said secondary of said second transformer, said output of said third pulse amplifier connected to said primary of said third transformer, and said pulse input connected to one of said microcomputer output lines, said third pulse amplifier operable to control the safety device via said third transformer in response to the operation of said second pulse amplifier and data on said one microcomputer output line.