Being able to respond flexibly to business opportunities is essential for the manufacturing industries to stay competitive. Making flexible use of the plant floor equipment is an essential aspect to this. The research presented proposes an approach to automation systems design and implementation, focusing on (but not limited to) batch processes and derived from the ISA-88 standard, with the aim of minimising the programming effort required for a new product by following a modular approach. Particular attention is given to implementing the interfaces between system modules in an open manner using the OPC UA communication standard.