# Pulse energy meter and Arduino Yun

Hi,

I'm trying to measure the energy of a circuit by using this meter but i'm not understanding the circuit that i need to assemble in order to detect the pulses from that meter on the arduino.

Can someone point me in the right direction?

Page 4 of the linked datasheet shows a bar-bones schematic for an interface circuit. As I read that schematic, Uimp is a DC voltage source, and RL is a current-limiting resistor. I believe that the output appears on pin 20 as a voltage that pulses between nearly zero and nearly Uimp.

As for how to connect it to a digital Arduino input, it’s not entirely clear to me what the best course would be. The datasheet claims, on page 3, that the output conforms to the requirements for a type SO output under standard EN62053-31, Class A. That standard seems to allow for a certain amount of leakage current through the output circuit, so it’s not obvious what the voltage will be on the output when the output is off.

I’ll suggest two alternatives:

• Use a 12 volt source, and pick a load resistor in the middle of the range. Connect pin 20 to the input of a comparator powered from Uimp, and connect a voltage divider to the other input of the comparator. That should give you an open-collector output from the comparator that indicates the status of the meter’s output.
• Use a 12 volt source, and pick a load resistor in the middle of the range. Connect the LED of an optocoupler between RL and pin 20, and take the Arduino input from the collector of the phototransistor, using a reasonable resistor between the collector and the Arduino’s 5V - maybe something like 10K. That will work if the leakage through the output is quite low when the output is off. If the leakage is too high for the optocoupler to cut off, then you might have more experimenting to do to get it to work reliably.

The link is broken for me.

It is not a "Pulse energy meter", it is an energy measuring device that outputs pulses to indicate power used. If I'm reading it correctly, one 70ms pulse per Wh (watt hour) of energy consumed.

I'm not certain, but I think the output is just a switch. That an external circuit must supply "U", which seems to mean voltage in this case, and it is rated for 12 to 27Vdc. I don't know if it will work on 5V. If not, you can use 12V with a resistive voltage divider so it only sends 5V to the Arduino.

The output is switch-esque, I think. It could be as simple as the uncommitted collector and emitter of an optotransistor, or it might have a reverse-voltage protection diode, a low-value series resistor, a parallel zener diode, and maybe transient suppression, too. "Class A," the output standard for long distances, suggests that it may have more, rather than less, protection.

The standard, EN62053-31 type SO - seems to allow for a lot of leakage in the off state - on the order of several milliamps - so it may be tricky to get a signal with clear values.

I've seen a couple of posts asking about similar devices. I think maybe something from Iskra? But I don't recall seeing anything that said, "here's the universal interface circuit."

Ugh. There are days I truly hate international standards groups like the IEC. For \$100 you can buy a 37 page document from the IEC about the interface. Or, for even more money, you can buy the exact same document from someone like Amazon.

The key-phrase is "IEC 62053-31" not "EN62053-31".

In any case, it is describe as a "pulse generator" which I take to mean there is a circuit that stores energy as the meter measures power then dumps the stored energy as a modest sized pulse. That energy is dumped into whatever circuit is on the outside.

I suspect the intent is to drive an LED; either a visible LED so a human can tell if power is being consumed or the LED of an optocoupler. My suspicion is that the standard allows the pulse to be a range of voltages (e.g. 12 to 27 VDC from the IME document) which, when connected to an LED + current limiting resistor, would equate to a range of currents (e.g. 10 to 27 mA).

If anyone here can read Russian, I found a website where the standard is illegally published.

OK, attached is an app note from SAIA Burgess Controls, whoever they are, showing a few possible configurations for an EN62053-31 type SO output, along with a couple of configurations for the interface.

The output is the transistor side of an optocoupler, maybe with protection circuitry. The energy for the pulses comes from an external power supply, and there’s an external limiting resistor in series with the output. The circuits shown would give an ON voltage ranging from the saturation voltage of the output phototransistor to maybe a volt, and an OFF voltage ranging from a high of nearly the input supply voltage to something dependent on the value of the internal zener diode, the internal limiting resistor, and the external limiting resistor. All of that is consistent with the abbreviated schematic in the OP’s datasheet.

The purpose of the output isn’t entirely clear to me. SAIA offers a pulse counter that can be driven directly from the pulse output, presumably to provide a remote reading of the meter for, maybe, a customer, while keeping the meter itself in a secure enclosure to prevent tampering. The pulse output might serve as the input to a pulse recorder, so that the utility can analyse the pulse rate and thus the average power over an interval, to calculate a demand charge for customers that have to pay them. My experience with electric metering says that a new meter - say, electronic as opposed to electromechanical - have to be backward-compatible with a couple of generations of the previous technology - say, electromechanical meters with pulse initiators - if they want utilities to even consider buying them.

In the attached document, some of the possible configurations show an internal series resistor and a parallel zener diode. If the diode voltage is lower than the external DC supply, some non-zero current will flow through the output. It’s not clear to me what levels are permissible, but it might be more than some minuscule value. So, it’s possible that it’s hard to get very close to the voltage of the external supply on the output.

If the actual circuit is anything like the examples, it might be possible to use it with 5V and a fairly big resistance, say 10K, without any other interface circuitry, and connect directly to an Arduino digital input. Or, that may not work, if the voltage drop across the reverse-protection diode is too big, the internal limiting resistor is too big, or the ON voltage of the transistor is too high. Whatever the output is for, it doesn;t look like it’s intended to be super-friendly to 5V microcontrollers.

Thank you for all the replies.

My knowledge in electronics is limited but using the information provided in your answers couldn't i connect an optocoupler to the output of the measuring device using a 470 ohm resistor and then connect the arduino vcc to a 10k resistor wich is then connected to the optocoupler and then to a arduino digital pin? (Similar to what tmd3 said in it's second suggestion but assuming that the measuring device has a internal power supply)
Or am i missing something?

Regards

… assuming that the measuring device has a internal power supply

The metering device surely has its own power supply. But, I don’t see any evidence that the meter’s supply is available to the pulse output. I’m fairly sure that the pulse output is isolated from the meter, to avoid concerns about whether a remote device connected to the pulse output has its own power supply, and whether it’s connected in a way that doesn’t interfere with the meter.

Here’s why I think that:

1. The datasheet that you linked to shows a "Uimp, that appears to be an external voltage source
2. The datasheet that you linked to shows a voltage range for Uimp. If the voltage source Uimp were derived from the meter, there’s no reason to describe a range.

The pulse output might work as a direct input to the Arduino, with an external high-value resistance connected to the Arduino’s own 5V supply. Or, it might not.

Hm i can see you point there. I ended up ordering one and will give some feedback just in case some one needs this info in the future. I'll start by checking exactly this, if those pulse output pins provide any voltage and go from there.

Thanks for all the help.

Hi everybody .

I want to connect arduino with optocoupler and pulsation .. how will do it ?

how will program that by arduino program using interrupt ?

Sincerely

Alaa_Al_Hassan:
Hi everybody .

I want to connect arduino with optocoupler and pulsation .. how will do it ?

how will program that by arduino program using interrupt ?

Sincerely

Hello Alaa. Welcome to the Arduino forum.

Please begin your own thread stating which Arduino you have and which optocoupler and describe the pulsation and where it is coming from.

Have you any beginning code for your program? If so, kindly post it as well.

Paul