Today's manufacturing environment is characterised by significant change in the way it is able to respond to its business objectives. Companies now face new challenges to meet customer demands including greater flexibility, a wider range of products, higher quality, improved lead time, whilst maintaining _c.ompetitive prices. The changes manifest in each company will differ but, the trend is towards providing a leaner, more responsive organisation. This is reflected in the need for Information Technology (IT) systems to be more integrated across an enterprise and for the systems to be provided on a distributed basis. At the same time it is imperative that the costs associated with these IT systems and the range of skills required by an enterprise to develop and support such systems should be minimal. One way of achieving this objective is to adopt the use of standards. During recent years there has been a lot of activity to standardise the way that manufacturing devices communicate with each other. Considerable progress has been made, thanks not least to the success of the international effort of stand­ ardisation bodies like ISO, IEEE and IEC, and projects applying standardised protocols like Manufacturing Automation Protocol (MAP), in the USA, Commun­ ications Network for Manufacturing Applications (CNMA) in Europe and not forgetting Mini-MAP and Fieldbus technology.