Before any grumpy electricians jump on me, I understand this is a super basic question that's google-able, but I cannot find the exact answer I'm looking for, even on these forums.
I'm a computer science student working for my uncle's security company. I was asked to make a more budget-friendly version of a specific security/access control system for a client. It has many components, but after some research, I am almost certain my idea will work.
Without giving any useless info about the entire layout, the idea is that boaters will click a key-fob which activates the AccessPro AP-5, which in turn uses one of its relays to activate whatever you want to hook up to it; a gate, or whatever. I was originally planning to have the Arduino Mega read the voltage across COM-NO by using a voltage divider, but upon investigation, there is no voltage or current across the terminals. However, I know they work because I used my meter to continuity check COM-NC and COM-NO after activating the unit.
My question is this: how can the Arduino read if COM-NO is closed if there's no current or voltage to read? I'm new to Arduino but I know some C code from my intro class and some basic electronics stuff from high school.
If this has already been answered exactly as asked, I would appreciate anyone linking me to that!
