Gateway device, gateway control method, and non-transitory computer readable medium

A gateway control method for controlling a gateway device that relays communication of safety data between a safety input/output unit and a safety controller that controls the safety input/output unit so as to establish a safety connection between the safety input/output unit and the safety controller, the safety input/output unit and the safety controller being included in a safety control system, the gateway control method comprising:

• managing a control state that is a state corresponding to a state of the safety control system and is one of a safety state and a non-safety state, and controlling a state transition of the control state by applying safety data that the gateway device has received from the safety input/output unit to state transition information that indicates a state transition concerning the control state;
• and
• generating, when the control state has transitioned from the non-safety state to the safety state, safety data that indicates the safety state and is to be transmitted to the safety input/output unit.

A non-transitory computer readable medium storing a gateway control program to control a gateway device that relays communication of safety data between a safety input/output unit and a safety controller that controls the safety input/output unit so as to establish a safety connection between the safety input/output unit and the safety controller, the safety input/output unit and the safety controller being included in a safety control system, the gateway device being a computer, the gateway control program causing the gateway device to execute:

• a state monitoring control process of managing a control state that is a state corresponding to a state of the safety control system and is one of a safety state and a non-safety state, and controlling a state transition of the control state by applying safety data that the gateway device has received from the safety input/output unit to state transition information that indicates a state transition concerning the control state;
• and
• a safety control process of generating, when the control state has transitioned from the non-safety state to the safety state, safety data that indicates the safety state and is to be transmitted to the safety input/output unit.