Pnp and Npn mainly refers to the input modules. Output modules are mainly relay outputs. So when you turn on the output what you have wired as a source voltage will be what is on the output you turn on. So using your drawing you have a +24Vdc source, and when you turn on any output you will see +24Vdc on it. Now by the diagram on the solenoid you need pin 1 wired to the output and pin 2 wired to common. The last pin is the ground. I hope this helps.