Method and an arrangement for synchronizing two or more communication networks of the time multiplex type

An arrangement for synchronizing two or more individual communication networks of the time multiplex type, for forming a composite network thereof, said individual networks having nodes via which cyclic transmission of time frames is performed, said time frames including a plurality of time slots intended for data transmission, comprising:

• one node of the composite network being assigned as a superior master node, for determining a frame transmission rate of the composite communication network, which includes
• means for forming a fixed idle pattern, common to the composite network, for obtaining synchronization between the individual communication networks, and a fixed triggering pattern, and
• means for adding said idle pattern to each time frame transmitted from said superior master node, followed by said fixed triggering pattern wherein said fixed triggering pattern indicates a start of a next time frame,
• one node of each of said individual networks being assigned as a master node for synchronizing the data transmission of the respective network, said master node including means for starting, at the receipt of the triggering pattern therein, transmission of a new time frame from the master node,
• wherein said means for starting transmission of a new time frame from a master node includes:
• a counter, a cycling time of which is similar to a cycling time of a time frame minus the length of the idle pattern, and
• a triggering pattern comparator having means for storing the fixed triggering pattern and for comparing it with and identifying a triggering pattern of an incoming time frame,
• said counter being connected to the comparator for transmitting, after having finished a count, a signal to the comparator to begin detection of an incoming triggering pattern.