Signal exchange procedure via serial bus - selectively transmitting byte or bit oriented data telegrams from central exchange

摘要

An input and/or output unit is coupled to the serial bus. Signal exchange is carried out by data telegrams. These, transmitted from the central exchange, are selectively byte or bit oriented. The byte oriented data telegrams contain at least one address byte, while the bit oriented data telegrams contain a bit for each input and/or output unit. Each data telegram starts with a synchronisation sign, followed by a control byte and at least a data byte. The data byte of a data telegram, each consisting of 8 bits, alternate with individual bits of 1 logic level. In a byte oriented data telegram, the synchronisation sign is followed by a control byte, an address byte, and a weighting byte. USE/ADVANTAGE - Signal exchange between the exchange and subscriber stations in dependence on type of transmitted data.