Communications network control method

Claim 1

A method of controlling a communications network which includes a plurality of node devices connected so that a tree-like hierarchical structure is formed, each of said node devices having a single high-order direction port and a plurality of low-order direction ports, the communications network including a plurality of transmit/receive stations each being connected to one of the node devices via an interface device, each of the transmit/receive stations having an input port and an output port connected to the node devices via the interface and transmitting a signal when there is no signal at the input port, a highest-order node device out of the node devices in the communications network broadcasting a first-arrival signal which is received by said highest-order node device, said first-arrival signal being one of signals which are transmitted by some of transmit/receive stations at almost the same time, signals other than the first-arrival signal being discarded, said method comprising the steps of: (a) storing, in a buffer provided in said interface device and arranged so as to receive a signal via said one of the node devices, a first input signal received by said interface device from said one of the node devices approximately concurrently with a second input signal received by said interface device from one of the plurality of transmit/receive stations; and (b) transmitting the first input signal received from said one of the node devices and stored in said buffer in the step (a), to a destination transmit/receive station after the second input signal from said one of the plurality of transmit/receive stations is no longer received; wherein the buffer comprises a FIFO memory and further comprising the steps of: (c) storing said first input signal received from said one of the node devices into a first input of the FIFO memory provided in the interface device, said FIFO memory having a second input parallel to the first input; (d) writing a space signal into the second input of the FIFO after the first input signal ends; (e) transmitting a collision presence signal from the interface device to said one of the transmit/receive stations which transmits the second input signal when the first input and the second input signal arrive at the interface device at almost the same time; and (f) transmitting the first input signal written into the first FIFO input to said one of the plurality of transmit/receive stations which transmits the second input signal in response to receipt of the collision presence signal.

Claim 2

A method of controlling a communications network which includes a plurality of node devices connected so that a tree-like hierarchical structure is formed, each of said node devices having a single high-order direction port and a plurality of low-order direction ports, the communications network including a plurality of transmit/receive stations each being connected to one of the node devices via an interface device, each of the transmit/receive stations having an input port and an output port connected to the node devices via the interface and transmitting a signal when there is no signal at the input port, a highest-order node device out of the node devices in the communications network broadcasting a first-arrival signal which is received by said highest-order node device, said first-arrival signal being one of signals which are transmitted by some of transmit/receive stations at almost the same time, signals other than the first-arrival signal being discarded, said method comprising the steps of: (a) storing, in a buffer provided in said interface device and arranged so as to receive a signal via said one of the node devices, a first input signal received by said interface device from said one of the node devices approximately concurrently with a second input signal received by said interface device from one of the plurality of transmit/receive stations; and (b) transmitting the first input signal received from said one of the node devices and stored in said buffer in the step (a), to a destination transmit/receive station after the second input signal from said one of the plurality of transmit/receive stations is no longer received; wherein the buffer comprises a FIFO memory and further comprising the steps of: (c) storing said first input signal received from said one of the node devices into a first input of the FIFO memory provided in the interface device, said FIFO memory having a second input parallel to the first input; (d) writing a space signal into the second input of the FIFO after the first input signal ends; (e) transmitting a collision presence signal from the interface device to said one of the transmit/receive stations which transmits the second input signal when the first input and the second input signal arrive at the interface device at almost the same time; and (f) transmitting the first input signal written into the first FIFO input to said one of the plurality of transmit/receive stations which transmits the second input signal in response to receipt of the collision presence signal.