I have a SainSmart 8 Relay Module hooked up to an Arduino nano. I am a bit confused with the status of this module. As an example, I have D2 of the Arduino board hooked up to relay #1.
When D2 is high (5V) then the LED for relay #1 is off When D2 is low (0V) then the LED for relay #1 is on
This is totally counter intuitive. If I have a signal to the pin then the LED should be on, and if there is no signal it should be off. The only way I can explain this is if they light the LED because they want to indicate the NO status. However, that doesn't make any sense because there are both NO and NC pins so there is no preference.
Now if I look at the actual output, the normally open connection is closed (connected) when my input is low (0V) and the normally open connection is open (disconnected) when my input is high (5V). So that also indicates that the status of the LED shows the NO status (it's off when disconnected, on when connected).
So basically I have
Input LED NO NC 0V on closed open 5V off open closed
This is confusing. I would expect that if I have an input of 0V the LED is off and the NO is open (disconnected). Instead, when I have 0V the LED is on and the NO is closed. What am I getting wrong?