Hi dancurtin,
Welcome to the Tech Forum.
Just to clarify, to which specific part number are you referring? From what you describe, it will most likely work, but I’d like to check the documentation of the specific part to verify.
However, in general, an “open drain” output means that the output will sink, rather than source current. This means that it requires an external power supply of no more than 24V, and in your case, you would apply 12V to the “+” contact of your light and you would connect the “-” side to the open-drain output of the MultiTech device.
See this Forum post for further explanation of how “Open Drain” outputs work.