KirkC
Member
I want to read the pulse output from an ABB mag flow meter with a Modicon BMXDDI1602 discrete input module (positive 24VDC sinking). I will only get a pulse about once per minute so I don't need an HSC module.
The ABB book (see attached) shows a diagram for the pulse output, passive, optocoupler. I think I need this one, not the active one. The diagram shows a resistor, R(b). I do not understand what this resistor is for or what value it should have. The book gives a calculation for the value. I'm guessing the U(ce) is the 24 volts, but what is I(ce)? Doesn't the discrete input module itself act as a load?
Thanks for helping!
The ABB book (see attached) shows a diagram for the pulse output, passive, optocoupler. I think I need this one, not the active one. The diagram shows a resistor, R(b). I do not understand what this resistor is for or what value it should have. The book gives a calculation for the value. I'm guessing the U(ce) is the 24 volts, but what is I(ce)? Doesn't the discrete input module itself act as a load?
Thanks for helping!