olemus
andmeedastuse tehnoloogia, mis põhineb
mõõdetavatel voolutugevuse väärtustel
=
a data transmission technology based on measurable values of electrical current

ülevaateid
https://en.wikipedia.org/wiki/Current_loop

https://en.wikipedia.org/wiki/Digital_current_loop_interface

https://www.predig.com/indicatorpage/back-basics-fundamentals-4-20-ma-current-loops

http://www.bapihvac.com/wp-content/uploads/2010/07/Science-of-4-20-mA-Current-Loop.pdf

http://educypedia.karadimov.info/library/curentlp.pdf