A system and method for creating and incorporating a function block within a process control system enables a user of the process control system to generate a function block by combining a plurality of files selected from a group of files provided by the manufacturer of the process control system to form a source code file associated with the function block. The user can modify the function block source code file to include a procedure, routine or algorithm that is not provided by the manufacturer and can send the modified source code file to the manufacturer for validation. If the function block source code file is validated, a security measure such as a digital signature is provided to the user that enables the user to incorporate the function block within the process control system. The function blocks can be used to incorporate anew function into a process control application or to operatively integrate a data source external to a process control application with the process control application via data mapping functions performed by the function blocks.