Reviewed resource: Modbus for process control and automation
Modbus is one of the older industrial networking protocols that is still commonly used in process plants. While some regard it as a legacy technology that should be scrapped in favor of more sophisticated fieldbus and Ethernet based platforms, it performs well in many applications, including down to the instrumentation level for remote I/O devices. In a whitepaper available in the Resource Center at www.controleng.com , Moore Industries discusses what Modbus can do today and how to use it in your plant environment.
For a platform that’s almost 30 years old, Modbus has been resilient and adaptable, adding Ethernet and wireless connectivity to increase its versatility. Moore’s paper includes configuration suggestions for individual instruments, for transmitting HART diagnostic data, and for communication between DCSs and analog input modules.
Modbus does not have all the functions of a current fieldbus platform such as Foundation Fieldbus or Profibus PA. By comparison, there are few diagnostic capabilities and no way to send power to individual instruments. On the other hand, it is inexpensive, easy to work with, and there are devices available from a wide variety of manufacturers that support connectivity.
—Peter Welander, process industries editor, PWelander@cfemedia.com , Control Engineering Weekly News