relaywiring
I am attempting to wire this relay http://www.canakit.com/4-port-usb-relay-controller.html to this lock http://www.southco.com/en-us/em-05. I have done some work with Arduinos before, but I am not an electrical engineer, therefore I am having trouble figuring out how to wire these 2 together in order to get the relay to power (and open) the lock. Any help would be appreciated!
The relay channels each have NC, COM, and NO.
The lock has GRD, POW, SIG, COM, and NO.
Yes, that would work. Depending on the power of these appliances and your local jurisdiction, you may be required to switch both the hot and neutral with DPST (double pole single throw) relays.
There is a schematic available as one of the product photos on the page you linked:
This shows that of the three contacts associated with each relay, the center one is the common connection, one of the others is a normally-open contact, and the third is normally-closed.
Which of the actual physical pins is NC and which is NO isn't obvious from the photos and schematic, but there may be some indication in the silkscreen that isn't visible in the photos. In any case, it would be really easy to check by, for example, just hooking up a desk lamp or something through the relay on one or the other side.
You could equally well (and more safely) use a multimeter to measure the resistance from either side to the center contact and determine which is NC and which is NO.
Best Answer
Connect the lock's brown Ground to the power supply negative terminal, and the red Power lead to the power supply positive. Also connect a relay "COM' terminal to the power supply positive. Connect the relay "NO" terminal to the lock's orange control wire.
The lock's microswitch terminals could be used to provide an indication that the lock has actually operated.