The 4–20 mA convention was born in the 1950s as electronics became cheaper, and the reliability met the automation industry’s requirements. 4-20 mA provided a low-cost, easy to use solution, not subject to major signal line losses. In the 1980s and 1090s, several organizations and device manufacturers started engineering the first fieldbuses, like, for example, PROFIBUS. Fieldbuses enable 2-way digital communication.
PROFIBUS vs. 4-20 mA
This video explains one of the most dramatic evolutions in industrial automation: the transition from 4-20 mA to digital fieldbuses. It compares the two and highlights key benefits and new business models arising from the implementation of fieldbuses.