Evaluation system, non-transitory storage medium storing thereon evaluation program, and evaluation method

A non-transitory storage medium storing thereon an evaluation program for evaluating functional safety of a safety program for causing a target device to operate with safety maintained, when a predetermined condition is satisfied, the evaluation program, when executed by a processor, causing the processor to perform:

• acquiring the safety program, the safety program including a combination of instructions for determining a value or values of one or more output signals for one or more input signals;
• extracting, from the instructions included in the safety program, an instruction directed to processing for causing the target device to operate with safety maintained;
• extracting an input signal and an output signal related to the instruction extracted from the safety program;
• displaying the extracted input signal and the extracted output signal in association with each other, and receiving a setting of an expected output value for the displayed output signal, the expected output value being a value for causing the target device to operate with safety maintained;
• changing a value of the extracted input signal and determining whether a value of the output signal calculated by an operation in accordance with the safety program, in response to change of the value of the input signal, is identical to the expected output value;
• and
• wherein the evaluation program further causes the processor to perform extracting a type which is set for the instruction related to the extracted input signal, and
• the extracted type is one of:
• a first type defining that, when the value of the input signal is changed to an input value which indicates a condition for causing the target device to operate with safety maintained and thereafter the value of the input signal is restored to an original input value, an output value of a corresponding output signal should be restored to an original value following the value of the input signal being restored to the original input value;
• and
• a second type defining that the output value of the corresponding output signal should not be restored to the original value until a predetermined reset condition is satisfied.

An evaluation method for evaluating functional safety of a safety program for causing a target device to operate with safety maintained, when a predetermined condition is satisfied, the evaluation method comprising:

• acquiring the safety program, the safety program including a combination of instructions for determining a value or values of one or more output signals for one or more input signals;
• extracting, from the instructions included in the safety program, an instruction directed to processing for causing the target device to operate with safety maintained;
• extracting an input signal and an output signal related to the instruction extracted from the safety program;
• displaying the extracted input signal and the extracted output signal in association with each other, and receiving a setting of an expected output value for the displayed output signal, the expected output value being a value for causing the target device to operate with safety maintained;
• changing a value of the extracted input signal and determining whether a value of the output signal calculated by an operation in accordance with the safety program, in response to change of the value of the input signal, is identical to the expected output value;
• and
• extracting a type which is set for the instruction related to the extracted input signal,
• wherein the extracted type is one of:
• a first type defining that, when the value of the input signal is changed to an input value which indicates a condition for causing the target device to operate with safety maintained and thereafter the value of the input signal is restored to an original input value, an output value of a corresponding output signal should be restored to an original value following the value of the input signal being restored to the original input value;
• and
• a second type defining that the output value of the corresponding output signal should not be restored to the original value until a predetermined reset condition is satisfied.