Fault processor for programmable controller with remote I/O interface racks

In a programmable controller having a processor which executes control program instructions stored in a controller memory to operate devices on controlled machines which connect to said processor through a plurality of controller interface racks, the improvement therein of a fault processor which comprises:

• means for detecting faults associated with said interface racks;
• a plurality of storage means, each storage means being associated with one of said interface racks and each being connected to said detecting means for storing a detected fault associated with its interface rack;
• a disable line connected to said controller processor to force the deenergization of operating devices addressed by executed program instructions when the line is in a selected logic state;
• a set of logic gate means, each logic gate means being associated with one of said interface racks and each having an input connected to one of said interface racks and each having an input connected to one of said storage means and an output connected to said disable line;
• and
• a decoder connected to said controller memory to receive control program instructions stored therein and having a set of outputs each coupled to one of said logic gates means, said decoder being responsive to special program instructions read from said controller memory to selectively enable said logic gate means to generate said selected logic state on said disable line when a detected fault is stored in their associated storage means.

A programmable controller which comprises:

• a controller memory which stores an input image table, an output image table and a control program;
• a controller processor for executing the control program to control the state of output status bits stored in said output image table in response to the state of input status bits stored in said input image table;
• an I/O scanner connected to said controller memory and including means for periodically interrupting the operation of said controller processor, means for coupling a byte of input status bits to said input image table during an interrupt, and means for coupling a byte of output status bits from said output image table during an interrupt;
• an interface rack remotely located from said I/O scanner and connected to a controlled machine to operate devices thereon in response to the state of received output status bits and to monitor the state of sensing devices thereon and generate corresponding input status bits;
• cable means linking said I/O scanner and said interface rack;
• first transmitter means located at said I/O scanner and connected thereto to receive bytes of output status bits, said first transmitter means having an output which connects to the cable means for serially transmitting thereon each received byte of output status bits;
• first remote receiver means located at said interface rack and connected to said cable means to receive said output status bits serially transmitted by said first transmitter means;
• first remote transmitter means located at said interface rack and connected thereto to receive input status bits, said first remote transmitter means having an output which connects to the cable means for serially transmitting thereon each received input status bit;
• and
• first receiver means located at said I/O scanner and connected to said cable means to receive said input status bits serially transmitted by said first remote transmitter means, said first receiver means being operable to convert said serially received input status bits to bytes of input status bits for coupling to said controller memory by said I/O scanner.