A method of communication between a master unit and a slave unit, including the steps of: sending at least a command byte from the master unit to the slave unit including data byte counter bits to be interpreted by the slave unit according to the following rule set; if said data byte counter bits belong to a first set, then said data byte counter bits contain information representing a number of associated data bytes, which is the expected number of data bytes; if said data byte counter bits belong to a second set, then said data byte counter bits contain information representing a number which must be decoded before the expected number of data bytes is obtained; receiving at least the command byte; interpreting the command byte; and receiving the number of data bytes required by the rule set.