Fault tolerant data exchange unit

A fault tolerant data exchange system for use in conveying data in a redundant computer system having a plurality of channels, comprising:

• (a) a plurality of data exchange units, each associated with a different channel of the redundant computer system and each including:
• (i) a local data bus connected to the channel with which the data exchange unit is associated;
• (ii) a transmitter, connected to receive data from the local data bus that is distributed to each of the data exchange units;
• (iii) a multiplexer having an output and a plurality of inputs, each input connected to receive the data distributed from a different transmitter of the data exchange units for propagation through the output when selected by the multiplexer;
• (iv) means for initializing the data exchange unit so that it is synchronized with the other data exchange units;
• (v) receiver means, having a plurality of receiver inputs and a plurality of receiver outputs, for receiving the data selected for output by the multiplexer in each data exchange unit on a different receiver input and producing a corresponding output of the data thereby received;
• and
• (vi) voter means, connected to the receiver outputs, for selecting data from the receiver means for output from the data exchange unit according to predefined logic rules, so as to provide consistent data for all of the data exchange units, for said output, even when differences in the data input to the receiver means from each of the multiplexers are not the same;
• (b) first communication means for connecting the transmitter of each data exchange unit to a different one of the inputs of each multiplexer in the data exchange units;
• (c) second communication means for connecting the output of each multiplexer to a different receiver input of the receiver means of each data exchange unit;
• and
• (d) the second communication means including a plurality of consistency ports, each consistency port being associated with one of the data exchange units and having an input connected to receive the data selected for output from the multiplexer comprising said one data exchange unit, and a plurality of outputs, each connected to the receiver means in a different data exchange unit, the consistency ports each comprising a fault containment region that blocks propagation of faults within the data exchange system.

A method for transferring data from at least one source, so as to detect and compensate a fault in at least one channel of a fault tolerant system having redundant channels for communicating and processing data, the method comprising the steps of:

• (a) for each channel, distributing data produced by the at least one source over a local bus;
• (b) transmitting said data to the other channels over an inter-channel communications link;
• (c) selectively receiving the data distributed from each of the channels over the inter-channel communications link, in turn, for transmission to a consistency port associated with each channel that retransmits the data to all of the channels over separate communication lines;
• and
• (d) voting the data retransmitted from each of the consistency ports to select data that are output, the data thus selected compensating for at least one fault in the communication of data within the fault tolerant system.