Method of monitoring changes of state of a power transmission system by interruption signal transmission

• US 5,061,922 A
• Filed: 04/19/1989
• Issued: 10/29/1991
• Est. Priority Date: 04/22/1988
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Sakou, Eisaburo, Nakamura, Tomoharu, Nakamura, Mitsuru, Nishijima, Kazuo, Miyazaki, Terunobu
• Primary Examiner(s): Yusko, Donald J.
• Assistant Examiner(s): Holloway, III, Edwin C.
• Application Number:
  US07/340,470
• Time in Patent Office: 923 Days
• Field of Search: 340/825.06, 340/825.08, 340/825.12, 340/825.13, 340/825.5, 340/825.51, 340/825.07, 340/825.21, 340/825.05, 340/825.14, 340/310 R , 340/310 A, 370/85.6, 370/85.8, 370/95.2, 370/85.4, 370/85.5, 370/85.7, 370/95.1
• US Class Current: 340/9.1
• CPC Class Codes: G08B 26/002 only replying the state of the sensor
• CPC Class Codes: H04Q 9/14 Calling by using pulses

Abstract

A signal transmission/monitoring method for a system including a master station and a plurality of slave stations installed on and along a signal transmission line so as to be capable of mutually performing information transmission and reception in such a manner that the master station calls the slave stations through sequential polling with the called slave station sending reply information to the master station. An interrupt enable time zone is provided between a time point at which the call signal transmission from the master station is completed and a time point at which the reply signal transmission from the slave station is started. When other slave station issues an interrupt request within the interrupt enable time zone, signal transmission to the master station from that other slave station is carried out with priority.

Claims

1. A signal transmission method for a system in which a master station and a plurality of slave stations are installed on and along a signal transmission path so as to be capable of performing mutual transmission and reception of information comprising the steps of:

periodically transmitting a polling message, including a slave station address and a command, from said master station to respective slave stations in a predetermined sequence;

responding in a slave station to a receipt of a polling message directed to that slave station from said master station by sending a reply message, including its own slave station address and station information, to said master station a predetermined time after the polling message transmission from said master station is completed, wherein an interrupt enabling time zone is provided between a time point at which a polling message transmission from said master station is completed and a time point at which a reply message transmission from the slave station called by said master station is started; and

sending an interrupt reply message, including a slave station address and station information, during said interrupt enabling time zone from another slave station to which the transmitted polling message is not directed, so that upon issuance of said interrupt reply message by said other slave station within said interrupt enable time zone, the signal transmission from said other slave station which issues the interrupt reply message is permitted prior to that from said one slave station which has received a polling message directed to it.

2. A signal transmission method for a system in which a master station and a plurality of slave stations are installed on and along a signal transmission path so as to be capable of performing mutual transmission and reception of information in such a manner that said master station periodically calls said slave stations through sequential polling, comprising:

a first step in which, when one of said slave stations is called by said master station, the slave station address and information of said one slave station is sent out after lapse of a first time duration following the reception of the call signal from said master station;

a second step in which, when said one slave station is called, the slave station address and information of another slave station other than a said one slave station is sent out when a second time duration set shorter than said first time duration has lapsed from the reception of the call signal; and

a third step in which, when information of said other slave station is sent out while said one slave station is being called, sending of the information of said one slave station is delayed until after receipt of a next call from said master station to said one slave station.

3. A monitoring method for a system in which a plurality of slave stations for monitoring at least the operating states of associated pole switches and a master station for monitoring the states of said slave stations are installed on and along a power distribution line and are interconnected by said distribution line, comprising the steps of:

providing an interrupt enable time zone between a time zone in which a call command for designating a particular slave station is generated by said master station and a reply time zone in which the particular slave station designated by said call command sends information of its own state as a reply to said master station; and

when at least one other slave station, other than said particular slave station, in a group of the slave stations has its state changed after issuance of said call command to said particular slave station, said other slave station is allowed to issue an interrupt message including its own slave station address and station information within said interrupt enabling time zone, whereby upon appearance of the interrupt message on said distribution line within said interrupt enable time zone, sending of information of the other slave station which issued said interrupt message to the master station is allowed to be performed prior to that from said designated particular slave station within said interrupt enable time zone, while the sending of information of said designated particular slave station is delayed at least until the next call command is issued to said particular slave station from said master station.

4. A distribution system monitoring method according to claim 3, wherein said interrupt enable time zone is divided into a plurality of time sub-zones which are correspondingly correlated with types of changes in the state of the slave station, said types of state changes being allocated with priority levels in a sequential order in order to allow the slave stations which have undergone changes of state to issue interrupt messages in selected time sub-zones representing the priority levels correlated with the changes of state.

5. A distribution system monitoring method according to claim 4, wherein the priority level assigned to the change of the state of the slave station brought about by changing over of the pole switch from the open state to the closed state is set higher than the priority level assigned to the change of state of the slave station brought about by transition from a service interruption state to a service restoration state.

6. A distribution system monitoring method according to claim 3, wherein when the pole switch is automatically thrown into operative state upon transition of the associated slave station from the service interruption state to the alive state, the associated slave station is forcibly caused to stop issuance of the interrupt message brought about by the service interruption.

7. A distribution system monitoring method according to claim 4, wherein when the pole switch is automatically thrown into operative state upon transition of the associated slave station from the service interruption state to the alive state, said associated slave station is forcibly caused to stop issuance of the interrupt message brought about by the service interruption.

10. A distribution system monitoring method according to claim 4, wherein upon issuance of an interrupt message from a given one of the slave stations which has undergone a change of state assigned with a high priority level, the sending of information to said master station by said given slave station is performed with priority, while the sending of information to said master station from a slave station which has undergone a state change assigned with a lower priority level is delayed at least until the next call command is issued thereto until another call command is issued thereto from said master station.

8. A signal transmission method for a system in which a master station and a plurality of slave stations are installed on and along a signal transmission line in such a manner that said master station and said slave stations are capable of performing mutual reception and transmission of information with said master station calling said slave stations through sequential polling, in response to which the called slave station sends reply information to said master station, comprising:

a first step of setting as an initial value the identification number of a slave station to be monitored;

a second step of activating a first timer for managing a period in which said slave station is called when said slave station number has been set at said first step;

a third step for performing call transmission processing for the slave station to be monitored when said first timer is activated at said second step;

a fourth step of activating a second timer for designating a reply transmission start time of the slave station upon completion of said call transmission processing at said third step;

a fifth step of monitoring presence or absence of a reply, including a slave station address and station information, from a slave station following the activation of said second timer at said fourth step;

a sixth step in which, when it is decided that a reply is present from a slave station at said fifth step, a decision is made as to whether or not the time point at which the reply transmission from said slave station was started lies within an interrupt enable time zone which is provided between a time when a call signal transmission from said master station has been completed and a time when a reply signal transmission from the slave station called by said master station is started;

a seventh step in which, when a decision is made at said sixth step that the time at which the reply transmission from said slave station lies within said interrupt enable time zone, the slave station is identified as an interrupt slave station and data from the interrupt slave station is accepted by said master station; and

an eighth step in which upon reception of the data from said interrupt slave station, processing related to the reply transmission from said interrupt slave station is executed.

9. A signal transmission method for a system in which a master station and a plurality of slave stations are installed on and along a signal transmission line in such a manner that said master station and said slave stations are capable of performing mutual reception and transmission of information with said master station calling said slave stations through sequential polling, in response to which the called slave station sends reply information to said master station, comprising:

a first step of monitoring constantly a state in the slave station to be monitored;

a second step of setting a "state change flag" when a decision is made at said first step that the state of the slave station being monitored has undergone a change;

a third step of monitoring constantly the signal transmission line for a call from said master station when said "state change flag" has been set at said second step;

a fourth step of receiving data from the master station at once when a decision is made at said third step that a call from said master station is present;

a fifth step of deciding whether or not the call is for it'"'"'s own destination upon reception of the data from said master station at said fourth step;

a sixth step of checking whether or not the "state change flag" has been set, when it is decided at said fifth step that the call is not for it'"'"'s own destination;

a seventh step of starting transmission of an interrupt message, including a station address and station information, to said master station when it is decided at said sixth step that the "state change flag" has been set; and

an eighth step of resetting the "state change flag" upon completion of the interrupt message transmission started at said seventh step.