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Are you certain that there are two pulse outputs? The data sheet shows only one.

If there are two, then although I have never tried to do this, according to the Atmel Data Sheet (Page 70, Section 12: External Interrupts), you have two external interrupts, on pins PD2 & PD3. Therefore, provided that you do not need these I/O and the interrupts for any other purpose, you should be able to have one Arduino handle both inputs.

But do you need to have the two sets of pulses recorded separately? If you need to check your energy bill, then yes you do; but if you require only to measure your consumption, then you could wire the two S0 outputs in parallel and use one pulse input. There should be no problem since the S0 output is a transistor switch, and the pulses cannot overlap as it cannot be both day and night at the same instant!

To read the pulses, you need to include some code based on the example here in your sketch.

Some of the early versions of my Mk2 PV Router code were able to monitor activity.  The sensor is just an LDR plus a couple of passive components which are connected to any of the digital inputs.  The sketch polls the state of the sensor every mains cycle.  For  my supply meter, the pulse length is approx 38 ms, so pulses should always be detected when polled at a 50 Hz rate, i.e. once every 20 ms. 

Using this polling technique, there is no limit to how many LEDs can be monitored at the same time - other than the number of IO pins that are available.  Meter activity is displayed via the Serial monitor.

Mk2_PV_Router_mini_3.ino includes this feature.  There's a link to this code on my Summary Page.

Thanks for your answer.

I didn't control the eltako meter physically.  Maybe I should do that.  Onto the data sheet I noticed S0+ en S0-

That's the reason why i think there are 2 S0 pulse outputs.  Why do you think there is 1 output pulse?

I see why you think there are two outputs, but in fact there is only one. The S0+ is the positive connection and S0- is the negative connection. The output switch (probably a transistor) is connected between S0+ and S0-.
See http://de.wikipedia.org/wiki/S0-Schnittstelle#mediaviewer/File:S0-Schnit...
(Zähler = Meter - für alle, die Deutsch nicht versteht.)

thanks, you are right.  Now i understand.

what kind of cable do i need to connect the pulse meter with the emontx v2?  And where can I find it on your site?

Depending on the length you require, you can use a twisted pair of 'telephone', Cat3, or 2-core screened 'microphone' cable. If there are sources of interference - usually mains wiring feed fluorescent lamps or induction motors - close by, you might need to have screened cable, in which case you earth the screen at the meter end only. You will not find that in the shop.

if I use a twisted pair to connect the positive and the negative connection.  Then, I also need a 3.5" audio jack to connect to the emontx v2,right?  How do I know how to connect  the audio jacht to the wire?

ok, of i use a twisted pair to connect the pulse meter into the emontx the i need a 3.5 audio jack right?

i would like to know how to connect the wire front the pulse meter into the 3.5" audio jack.

Yes, you need a 3.5 mm "stereo" plug. Look at the circuit diagram for the emonTx V2 - there is a link on the Wiki.

Use a blob of solder to select either 3.3 V (V_CC) or PWR (5 V) supply next to R8 on the PCB, and you will need to fit R8 (10 kΩ) if it is not already fitted. Wire S0+ to the plug tip S0- to the plug ring. If your cable has a screen, earth the screen at the meter end only, do not connect it to the plug sleeve.

thx for your answer Robert

I ordered my emontx.  I hope that i succeed to make is work.  I'm a noob in electronics as you already  noticed.