I bought the Optical Utility Meter LED Pulse Sensor for my Easymeter Q3D power meter. It is connected to a counter unit which counter I read every minute by a one wire bus system to a Raspberry Pi, from there to my local EmonCMS.
I can make the unit count impulses when I use my flashlight. When I apply the sensor to the power meter the counter does not change.
I think it might be a “problem” of the used hardware. The counter unit has a debouncing integrated to prevent wrong counting. My guess is that the pulse sensor does open the contact when the light flashes but the impulse is so short that the counter does not acknowledge a valid signal.
First question: Is this correct? Does the sensor open the contact when the light blinks?
Second question: Can I (somehow) change this function to the other way round? So that I get a closed contact when the light flashes?
The sensor should output a TTL high (3.3 to 5v) when light level is detected. It’s not possible to invert this without extra logic. You should see the led on the rear of the pulse counter flash when a pulse is detected.
So the sensor should have a closed contact when the light flashes. That should be good for my case.
I can see the green led flashing, so the function is there. Perhaps the impulse is to short so my counter debounces the impulse.
Must think about if I can slow it down…
Ok, I rechecked my problem.
The sensor switches my counter unit to “active” when I connect it.
If I use a flash light on the sensor the counter goes to “inactive”.
If I connect the sensor to the LED at the power meter the counter stays active.
My original thought seems to be correct. The impulse from the flashing LED is so short that the counter unit sees this as an error due to the debouncing installed.
My only hope now is to build a transistor inverter to change the signal. Lets see if I can manage this.
Why is the optical pulse meter a closing switch? The standard for S0 counter units is an open collector, meaning an opening switch.
Why not stick to the standard in this area of use?
I think you do not understand the output of the sensor. The output is a voltage pulse, a low voltage when no light is detected and a high voltage (3.3 V - 5 V) when light is detected. It is not a closing contact. That is, it is not a mechanical (magnetic reed) switch, and it is not a transistor switch. You cannot use it on an input to the S0 norm.
You might be successful of you connect the pulse output between the S0- input and GND.
thanks for the clarification.
Anyway, the System works with the S0 counter as described. If I use a flashlight on the sensor the counter does change its state. So I would “only” need to reverse the signal.
But thanks for the Information, I will consider this in my planning.