I would like to acquire pulse informations from a french electrical meter. There is a picture of the outputs of this electrical meter.
These pulses vary in frequency and after acquisition, we can calculate the active power (M1) and the reactive power (M2) depending of these frequencies variations. As I understand this documentation, I have to power it at 24VDC (27mA maximum and 10 mA minimum) through MC Pin and take the signal back from M1 & M2. Also, it says one calibrated pulse ("Passing" state) is about 40 ms, 30 ms minimum.
My objective is to read these pulsation directly on the GPIO of the raspberry pi (this part already work, I tested it with a signal generator directly on the rasp).
The fact is, I need to lower this 24VDC signals to the classic 3.3V of the rasp GPIO. I think the best way to do it is to go with an optocoupler circuit. In principle, I shouldn't have problem to see the variation through the optcoupler as one pulse is at 30ms minimum.
I tried to calculate the resistor from typical optocoupler circuit but I'm not sure at all. I can't access to the electricity meter for know so I can't test it to verify. Moreover, the circuit may be used on other meters, the DC voltage needs to be between 18V and 27V and the current between 10mA and 27mA precisely.
Before I sent you the calculation of the resistors, can someone confirm that one of my schematics make sense for what I want to do ?