I’ve bought a 2-relay module, and as usual it came with no documentation. Here are the pictures:
(I’ve included the pictures attached as well just in case they remove the links).
I’ve been googling and I’ve found some info for (apparently) similar modules.
My main concern is how to wire the relay inputs (Normally Open, Common and Normally Closed). The printed symbol is not enough clear:
--\ K1 -- | \ | A B C
Which one are A, B anc C?
My second question is about the pins JD-Vcc, Vcc and GND in the left corner, of which JD-Vcc and Vcc already came jumpered. I’ve read that these are for an alternative power source so that the arduino only switches the LED in the octocoupler. I guess this alternate power source would be used to switch the relays. How do I know if I need to provide an alternate power source? What current and voltage would be needed, and why is the Arduino not able to provide it?
My third question is about the second group of pins in the right corner (GND, IN1, IN2, Vcc). I guess GND and Vcc should be wired to the arduino GND and 5V pins, and IN1 and IN2 control the relays state. I’ve read that for similar relay modules the inputs IN1 and IN2 are active low. Apparently, to ensure no relays turn on in startup or reset, this initialization would be required in the setup method:
digitalWrite(relay_pin, 1); pinMode(relay_pin, OUTPUT);
Is this the case with my relay module? If so, why do they write in the pin before configuring it as output?
Thanks in advance.