I just bought a 2-relay module.
From above it has CL2, CL1, DC- and DC+.
By using a 5V source I found that by connecting CL2 or CL1 to DC-, the relays closed. So there is no such thing as IN1 or IN2 that expect a HIGH signal from the board.
Will they work,i.e. make the relays work, at LOW? So I will put the pins to ground, I guess I should set them as INPUT_PULLUP and put them to LOW to make the relays work, am I OK or wrong?