Each relay can operate in one of the following modes:
RELAY_TYPE_NORMAL - High-level-trigger, normally open relay.
RELAY_TYPE_INVERSE - Either low-level-trigger, or normally closed relay.
RELAY_TYPE_LATCHED- Relay is controlled with two normally-low GPIOs, if set GPIO goes up the relay will turn on, if reset GPIO goes up the relay will turn off
RELAY_TYPE_LATCHED_INVERSE- Relay is controlled with two normally-high GPIOs, if set GPIO goes down the relay will turn on, if reset GPIO goes down the relay will turn off