W
Walter Harley
- Jan 1, 1970
- 0
Idle curiosity: What is the history of the 4-20mA standard for industrial
process control signalling? E.g., why those particular values; were other
values also used at some time; who developed the idea of current rather than
voltage signaling, and who first used it in industrial equipment? (All
Wikipedia says is that it dates to the 1950s.)
Thanks!
process control signalling? E.g., why those particular values; were other
values also used at some time; who developed the idea of current rather than
voltage signaling, and who first used it in industrial equipment? (All
Wikipedia says is that it dates to the 1950s.)
Thanks!