Network diagnostic apparatus

Apparatus for use with a data communication network having a plurality of nodes and including first and second data lines interconnecting said nodes, data bits on said data lines being represented by signals including a relatively high signal on one of said data lines and a relatively low signal on the other of said data lines, and including dominant and recessive bits to form sequential message frames, said apparatus comprising:

• a transceiver connected to said lines for receiving said data signals and generating an output stream of data signals in accordance with a protocol of said network;
• a data processor receiving said output signal stream of said transceiver and processing the same according to a stored program;
• at least first and second analog-to-digital converters having controlled sampling times and coupled respectively to said first and second data lines for generating in timed relation sampled digital signals representations of the voltage on each of said data lines of said network respectively, said data processor coupled to receive the output signals of said analog-to-digital converters;
• said data processor controlling said first and second analog-to-digital converters to sample a predetermined dominant bit in each of said message frames for each of said nodes on said first and second data lines respectively, to determine the respective values thereof at the same time in each message frame for each node, said data processor storing values for said data signals for each node in said network.