Due to recent progress in digital control systems, advances in communication methods and improvements in the functionality of modern sensors and controllers have resulted in the development of sophisticated communication systems in the automation, manufacturing and process environments. The communication systems, called the Fieldbus, contain hardware, software and protocols for interconnecting field devices used in the plant environment. The Fieldbus communication systems have access to the physical medium by the use of Data Link Layer (DLL) and the communication takes place by the protocols. The Fieldbus protocols are developed for distributed processes with centralized control philosophy (as in IEC/ISA Fieldbus and FIB) or distributed processes with distributed control philosophy (as in Profibus). At the moment, there are many fieldbuses offered by diverse range of vendors driven by commercial interests or application specific reasons. However, there is a worldwide attempt to standardize Fieldbus protocols so that it becomes independent of vendor or application specific requirements. This will allow the implementation of control strategies universally thus giving advantages such as improving intrinsic safety; giving better security; enabling easy installation, maintenance, monitoring and diagnostics of the equipment; resulting in interoperability; and yielding in the cost reduction for the vendors and ultimately for the end users.