Double ring network system and communication control method thereof, and transmission station, and program for transmission stations

A double ring network system including a plurality of transmission stations having any one thereof as a base station, and each respectively connected by a dual transmission line composed of a first communication line and a second communication line, the respective transmission station comprising a first communication port for receiving at one end side thereof left-handed information from the base station and outputting right-handed input information from the base station or information generated at this station in a right-handed direction from the one end side, and a second communication port for receiving at another end side thereof right-handed input information from the base station and outputting the left-handed information or information generated at this station in a left-handed direction from the other end side, to perform bi-directional communications in between, characterized in that

• the base station comprises, for an initial phase of startup,
• INZ frame transmitting means for transmitting right-handed and left-handed initializing first frames containing information having a source as the base station and a destination of transmission station designated, simultaneously from the first communication port and the second communication port, and
• the other stations comprise, for the initial phase of startup,
• INZ frame reception permitting means for permitting reception of information from the first communication port and the second communication port,
• first-come determining means for determining, when the first frames are received at the first communication port and the second communication port, the communication port having first-received said first frame,
• own station position identifying means for determining, when the right-handed and left-handed first frames having this station as a destination are received the right-handed at the first station and the left-handed at the second station, respectively, the station being positioned at a left-handed end or a right-handed end, whichever is in accordance with line lengths from the base station to this station and identification information of respective stations the right-handed and left-handed routed through as contained in the first frames, and outputting a terminal station setting signal to have set if it stands as a terminal station on either hand,
• first terminal station deciding means for operating with the terminal station setting signal output, for a result of the first-come determination that the first communication port has first received the right-handed first frame, to set the own station to be a terminal station mode at a left-hand end from the base station, transmit the left-handed first frame the second communication port has received temporarily to a left-hand adjacent station, and thereafter, stop sending information from the second communication port, and
• second terminal station deciding means for operating with the terminal station setting signal output, for a result of the first-come determination that the second communication port has first received the first frame, and the first communication port has received the left-handed first frame from a right-hand adjacent station, to set the own station to be a terminal station mode at a right-hand end from the base station, and stop sending information from the first communication port.

A transmission station for double ring network systems including a plurality of transmission stations having any one thereof as a base station, and each respectively connected by a dual transmission line composed of a first communication line and a second communication line, the respective transmission station comprising a first communication port for receiving at one end side thereof left-handed information from the base station and outputting right-handed input information from the base station or information generated at this station in a right-handed direction from the one end side, and a second communication port for receiving at another end side thereof right-handed input information from the base station and outputting the left-handed information or information generated at this station in a left-handed direction from the other end side, to perform bi-directional communications in between, characterized in that

• the base station comprises, for an initial phase of startup,
• INZ frame transmitting means for transmitting right-handed and left-handed initializing first frames containing information having a source as the base station and a destination of transmission station designated, simultaneously from the first communication port and the second communication port, and
• the other stations comprise, for the initial phase of startup,
• INZ frame reception permitting means for permitting reception of information from the first communication port and the second communication port,
• first-come determining means for determining, when the first frames are received at the first communication port and the second communication port, the communication port having first-received said first frame,
• own station position identifying means for determining, when the right-handed and left-handed first frames having this station as a destination are received the right-handed at the first station and the left-handed at the second station, respectively, the station being positioned at a left-handed end or a right-handed end, whichever is in accordance with line lengths from the base station to this station and identification information of respective stations the right-handed and left-handed routed through as contained in the first frames, and outputting a terminal station setting signal to have set if it stands as a terminal station on either hand,
• first terminal station deciding means for operating with the terminal station setting signal output, for a result of the first-come determination that the first communication port has first received the right-handed first frame, to set the own station to be a terminal station mode at a left-hand end from the base station, transmit the left-handed first frame the second communication port has received temporarily to a left-hand adjacent station, and thereafter, stop sending information from the second communication port, and
• second terminal station deciding means for operating with the terminal station setting signal output, for a result of the first-come determination that the second communication port has first received the first frame, and the first communication port has received the left-handed first frame from a right-hand adjacent station, to set the own station to be a terminal station mode at a right-hand end from the base station, and stop sending information from the first communication port.

A program for control of communications for double ring network systems including a plurality of transmission stations having any one thereof as a base station, and each respectively connected by a dual transmission line composed of a first communication line and a second communication line, wherein

• a respective transmission station comprising a first communication port for receiving at one end side thereof left-handed information from the base station and outputting right-handed input information from the base station or information generated at this station in a right-handed direction from the one end side, and a second communication port for receiving at another end side thereof right-handed input information from the base station and outputting the left-handed information or information generated at this station from the other end side, to perform bi-directional communications in between, wherein
• a respective transmission station comprising a first communication port for receiving at one end side thereof left-handed information from the base station and outputting right-handed input information from the base station or information generated at this station in a right-handed direction from the one end side, and a second communication port for receiving at another end side thereof right-handed input information from the base station and outputting the left-handed information or information generated at this station in a left-handed direction from the other end side, to perform bi-directional communications in between,
• characterized in that the program for control of communications for double ring network systems implements functions
• for the base station, for an initial phase of startup, as
• INZ frame transmitting means for transmitting right-handed and left-handed initializing first frames containing information having a source as the base station and a destination of transmission station designated, simultaneously from the first communication port and the second communication port, and
• for the other stations, for the initial phase of startup, as
• INZ frame reception permitting means for permitting reception of information from the
• first communication port and the second communication port, first-come determining means for determining, when the first frames are received at the first communication port and the second communication port, the communication port having first-received said first frame,
• own station position identifying means for determining, when the right-handed and left-handed first frames having this station as a destination are received the right-handed at the first station and the left-handed at the second station, respectively, the station being positioned at a left-handed end or a right-handed end, whichever is in accordance with line lengths from the base station to this station and identification information of respective stations the right-handed and left-handed routed through as contained in the first frames, and outputting a terminal station setting signal to have set if it stands as a terminal station on either hand,
• first terminal station deciding means for operating with the terminal station setting signal output, for a result of the first-come determination that the first communication port has first received the right-handed first frame, to set the own station to be a terminal station mode at a left-hand end from the base station, transmit the left-handed first frame the second communication port has received temporarily to a left-hand adjacent station, and thereafter, stop sending information from the second communication port, and
• second terminal station deciding means for operating with the terminal station setting signal output, for a result of the first-come determination that the second communication port has first received the first frame, and the first communication port has received the left-handed first frame from a right-hand adjacent station, to set the own station to be a terminal station mode at a right-hand end from the base station, and stop sending information from the first communication port.