Here are notes on how to resolve the FILE_OPERATION_DENIED error when using FILE operation functions in CODESYS.

Cause?

Starting from this version, access is restricted by default to files inside the PLC folder only. This is for security reasons.

Solution

You can allow the runtime to access files outside this folder, but you need to modify CODESYSControl_User.cfg. Below is the location of CODESYSControl_User.cfg on a WAGO PFC100.

Please add the following lines to that .cfg file.