Can someone explain to me the different types of solenoids and how they work?
I saw this on a website, and didn't know which one(s) to use. What is the difference between single, double, and relay solenoids?
Single and double solenoids refer to the physical characteristics of the solenoid. A Single solenoid has 1 control signal, and a default state when the control signal is not applied. A Double solenoid has 2 control signals, and the solenoid will retain the previous state when a control signal is not applied. The data sheet for your particular solenoid will tell you whether it is a single or double soleniod.
Whether you use the Solenoid VIs or the Relay VIs depends on how you wire the solenoid. If you wire it to the Solenoid breakout, you use the Solenoid VIs (either single or double as appropriate). If it uses a 12v activation signal, you have the option of using a single Spike relay to control it. If you do that, you would use the Relay VIs.