Hi
I want usemodule 8channel 5V relay as this:
I want use it with Arduino Mega and Raspberry pi. How i must connect it ? GND from RPI+Arduino+Relay i must connect together ? Please show me on image.... IS this relay has optoisolatio(optocoupler) ?
It is safety to use it in Home Automation ? I am begginner... please help me.
Do you only want to control it from the Arduino or also from the GPIO on the RP?
The outputs are isolated from the inputs. It also has opto isolation between the inputs and the relay driving coil but for that to you of course also need a separate power supply for that. (And you need t wire it correctly which I don't know how on your model). But luckily, you don't need that 
For the reset, DC+ to 5V, DC- to GND and all IN's you want to use to an Arduino pin.
Hi, Details on this here:
pepeEL:
I want use it with Arduino Mega and Raspberry pi. How i must connect it ? GND from RPI+Arduino+Relay i must connect together ? Please show me on image.... IS this relay has optoisolatio(optocoupler) ?
It is safety to use it in Home Automation ? I am begginner... please help me.
Yeah you have to common the grounds of all modules i.e. Arduino, Raspberry Pi and Relay modules.
Yeah this relay module has optocoupler already embedded on it. It's PC817, the black 4 pin chip in front of each relay.
Works perfectly for home automation projects. You just need to connect the pins i.e. Vcc & GND and the input pins to digital pins of Arduino Vs Raspberry Pi.
jackthom41:
Yeah you have to common the grounds of all modules i.e. Arduino, Raspberry Pi and Relay modules.Yeah this relay module has optocoupler already embedded on it. It's PC817, the black 4 pin chip in front of each relay.
LOL! For those two lines following each other 
IF you do the first you have NO optoisolation Not saying that's bad, works fine! But they could have just used a transistor.
