Relay does close when output pin i set to low

Hi guys.

I'm working on a project which requires some relay to close and open; the relays are NO - normally open.
I though I could achieve this simply by connecting the relay control pin to an Arduino output pin, which should be set to HIGH when I wanted the relay to be closed, LOW when I wanted the relay to be open.

This is the relay board I'm usign.

The problem I'm facing is: despite what I tought, the relay closes when the Arduino output pin is set to LOW (=0 Volts...), remains in his normal state (opened) when the pin is set to HIGH.

Output pin voltage has been measured with a voltmeter (pin LOW --> 0 Volts, but relay closed).
Can somebody help me figuring what's wrong?

Thanks :wink:

Verkia:
what's wrong?

Nothing.

Here's a good relay tutorial with explains "active low"

cattledog:
Here's a good relay tutorial with explains "active low"

Didn't know about the optocoupler. That's perfect!

Thanks man!!