Legacy systems that do not conform to the norms and regulations imposed by recent safety standards have to be upgraded to meet safety requirements. In this paper, we describe a methodology to upgrade legacy industrial applications based on the IEC61131 function block model without the need to redesign the whole application. We then describe an approach for automating the verification process of safety applications that is based on the use of the UPPAAL simulation and verification platform for embedded real-time systems. The meta-models of the source and target domains are presented and a transformation process of the PLCopen XML design specification to UPPAAL XML specification is described. A laboratory system is used as a case study to demonstrate the applicability of the proposed process.