Method for detecting failure and slave station for use in same

A method for detecting a failure in a control/monitoring signal transmission system in which a master station is connected with a plurality of slave stations via a common data signal line, and transmission of data is performed according to a transmission synchronization scheme, the method comprising:

• acquiring, by the slave station, control data of an output part corresponding to a first slave station from a transmission signal as well as acquiring monitoring data from a transmission signal, the monitoring data being referred by the first slave station and being based on input information from an input part of a second slave station, the input part being in a correspondence relation with the output part;
• obtaining, by the slave station, a pseudo input change timing equal to a true input change timing of the input part based on the monitoring data;
• comparing, by the slave station, a time difference between an output change timing of the output part and the pseudo input change timing with a first threshold value and a second threshold value;
• determining, by the slave station, a normal state when the time difference is larger than the first threshold value and smaller than the second threshold value, a first failure state when the time difference is smaller than the first threshold value, and a second failure state when the time difference is larger than the second threshold value;
• and
• causing, by the slave station, a signal configuring data indicating the first failure state or the second failure state to be superimposed on a management data region.

A slave station connected to a common data signal line to which a master station is connected, comprising:

• a synchronizing means for synchronizing with the master station;
• an input means for acquiring input information from an input part corresponding to the slave station;
• an output timing detecting means for acquiring control data of an output part which is in a correspondence relation with the input part from a transmission signal, and obtaining a pseudo output change timing equal to an output change timing of the output part;
• a failure detecting means for comparing a time difference between the pseudo output change timing and an input change timing of the input part with a first threshold value and a second threshold value, and determining a normal state when the time difference is larger than the first threshold value and smaller than the second threshold value, a first failure state when the time difference is smaller than the first threshold value, and a second failure state when the time difference is larger than the second threshold value;
• and
• a management monitoring data transmitting means for causing a signal configuring data indicating the first failure state or the second failure state to be superimposed on the management data region in the transmission signal.

A slave station connected to a common data signal line to which a master station is connected, comprising:

• a synchronizing means for synchronizing with the master station;
• a control data extracting means for acquiring control data related to an output part corresponding to the slave station terminal from a transmission signal on a common data signal line;
• an input timing detecting means for acquiring monitoring data to be referred by the slave station and being based on input information from an input part which is in a correspondence relation with the output part from the transmission signal, and obtaining a pseudo input change timing equal to a true input change timing of the input part based on the monitoring data;
• a failure detecting means for comparing a time difference between an output change timing of the output part and the pseudo input change timing with a first threshold value and a second threshold value, and determining a normal state when the time difference is larger than the first threshold value and smaller than the second threshold value, a first failure state when the time difference is smaller than the first threshold value, and a second failure state when the time difference is larger than the second threshold value;
• and
• a management monitoring data transmitting means for causing a signal configuring data indicating the first failure state or the second failure state to be superimposed on the management data region in the transmission signal.