SPDT is a no-go. This thing is really bizarre.
There are three terminals on the device, NO, COM, and NC.
Here are the combinations, starting with all three terminals unconnected.
1. Short NC and COM. Nothing.
2. Open NC and COM. Signal.
3. Short NC and COM again. Nothing.
4. Short NO and COM. Nothing.
5. Open NO and COM. Nothing.
6. Short NC and COM while NO and COM are shorted. Nothing.
7. Open NC and COM while NO and COM are shorted. Nothing.
8. Short NO and COM while NC and COM are shorted. Signal.
9. Open NO and COM while NC and COM are shorted. Nothing.
10. Short NC and NO. Nothing.
11. Open NC and NO. Nothing.
12.Short COM to NC/NO. Nothing.
13. Open COM while NC and NO are still shorted. Signal.
So there are three cases where a signal is sent. Opening NC and COM after they’ve been shorted; Adding NO to NC and COM already shorted; removing COM while leaving NC and NO shorted.
Dunno about you, but that logic leaves me scratching my head as to how I can connect an SPST or an SPDT and detect open and closed. I’d need some kind of logic gate, or a weird network of pull-up resistors.
To add insult to injury, I can’t tell WHAT signals are being sent, because any time I see the UT-3000 sending a signal, the EzSnsRf reports exactly the same four messages — on, on, off, off.