A method for managing soft errors associated with one or more safety programmable logic controllers (PLCs) is provided. The method includes receiving an expected soft error rate for type(s) of input/output (I/O) modules over time, receiving respective soft error data that was aggregated by the respective safety PLCs based on soft errors detected by I/O modules coupled to the respective safety PLCs. Actual soft error rates are determined per I/O module type based on the received soft error data, and soft error rates are predicted for the safety PLC(s) per I/O module type. The actual and/or predicted soft error rates are compared to the expected soft error rate per I/O module type. The method further includes taking one or more actions in response to a threshold deviation between the actual and/or predicted soft error rates relative to the expected soft error rate for the corresponding I/O module type.

Problems such as an operation stop of a controller caused by leaving out a mismatch requiring a change can be prevented. When a setting value is changed in a unit operation setting, an allocation management part specifies a storage capacity required for a storage of input data based on the changed setting value, and judges whether a mismatch occurs in an allocation state between the input data and a storage area specified in an I/O allocation setting.

A programmable controller sets access rules relating to permission or denial of access to a first data storage unit during execution of a second sequence program. In addition, a first sequence program is executed while accessing only the first data storage unit, whereas the second sequence program is executed while accessing the first data storage unit and a second data storage unit in accordance with the set access rules.

Problems such as an operation stop of a controller caused by leaving out a mismatch requiring a change can be prevented. When a setting value is changed in a unit operation setting, an allocation management part specifies a storage capacity required for a storage of input data based on the changed setting value, and judges whether a mismatch occurs in an allocation state between the input data and a storage area specified in an I/O allocation setting.

A programmable controller sets access rules relating to permission or denial of access to a first data storage unit during execution of a second sequence program. In addition, a first sequence program is executed while accessing only the first data storage unit, whereas the second sequence program is executed while accessing the first data storage unit and a second data storage unit in accordance with the set access rules.