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The switch is drawn as mechanical contacts (Manual section 3.3.1.1 - Outputs/inputs) but a polarity is shown, so I susspect the diagram is not absolutely correct, and there is a transistor there. But 3.3 V should be enough. Have you got the correct polarity?

You should wire 20 to your 3.3 V, 21 to your input pin. You must also provide a pulldown resistor, connected between 21 and GND. Section 7.1 Technical Specifications says 2 - 100 mA for the pulse output so I would try a 1 kΩ, if that fails try a lower value resistor but I would not go below 220 Ω, because of the maximum current allowed per processor pin.

When i read the manual, it says that the puls out operates from 5-40V, it looks like i have to connect the meter to 5V and use a resistor network to lower the voltage on the arduino due input.

i'm i right ?

Yes, that might be the problem - I did not find that section. In that case, you must connect 20 to your 5 V, and split the resistor into 390 Ω (nearest the meter - connect to 21) + 620 Ω (nearest GND) and take the junction of the two to the Due input.

But it might still work at 3.3 V.

The meter output worked when i switch it constant on or off i can see these status changes.

When the meter is in puls out mode, i can't see the puls, not even when i use the input in an interrupt.

maybe someone else has this kwh from abb and knows a way to get it working.

finaly solved it.

When constant turned on or off the 3,3V where enough.

But for the pulse it was to low.

Now i have a resistor network running on 5V and the pulses are comming through.

Next step send the power value to emoncms.

This is my schematic diagram but still i couldnot get any pulse in my com port from abb meter. I need some help or suggestions.

I did the same but still i see no pulse from my abb meter. I connected to 5v of Arduino to +20 and the other 21- to a 320 resistor  to Arduino interrupt pin and 680 ohm to ground. I  am so confused what went wrong with. Also the my arduino sketch is attached. Can anyone shed some light on it.

Do you have a 5 V Arduino? If so, why are you dividing the voltage down from ≈5 V to 3.26 V ? The minimum HIGH voltage for the interrupt to be seen is 0.6 V_CC = 3 V, so it should work but it is unnecessary. However, if the pulse output is only 4.8 V, the amplitude of the attenuated pulse is marginal, and it's not guaranteed to work. I've used 330 Ω in my calculation, as 320 Ω is not a standard value.

But you must use the divider if you have an emonTx running at 3.3 V.) Are you using the correct interrupt and pin?

I don't think it is a good idea to try to print to serial in an ISR. That is itself interrupt-driven, very slow and you will get into all sorts of trouble. Keep the ISR as short and as fast as possible. If you need to print on every pulse, set a boolean variable in the ISR and then check it in the main loop, and print from there.