Concurrent operation of processors in the bit-byte CPU of a PLC

The paper presents some selected hardware solutions for the PLC dual processor bit-byte CPUs, which are oriented at optimised data exchange between the CPU processors. The optimisation aims at maximum utilisation of capabilities of the two-processor architecture of the CPU. The key point is preserving high speed of instruction processing by the bit-processor, and high functionality of the byte-processor. The structure should enable the processors to work in concurrent mode as far as it is possible, and minimise the situations, when one processor has to wait for the other.