ABSTRACT
Most eldbuses or control system communication networks that have reached the stage of international or industrial standards are supported by user groups who maintain Internet sites. These sites contain lists of products and suppliers. For the systems covered in this section, the following is the list of products and suppliers:
AS-Interface (www.as-interface.com) HART (www.hartfoundation.com) PROFIBUS (www.probus.org) FOUNDATION eldbus (www.eldbusfoundation.org) ControlNet (www.odva.org) MODBUS (www.MODBUS.com) Ethernet/IP (www.odva.org)
INTRODUCTION
It has been 15 years since the authors rst contributed to the Instrumentation Engineers Handbook (IEH) with an article on networks in process automation (PA). In the last revision in 2001, we noted that the increase in computing power and the advance of Internet had caused signicant changes in PA with respect to the situation in 1995. Much has changed since then as the advances in the IT world continue to make a major in¶uence in PA.
