Direct Output module pins protection

Hello!

I'm trying to power a relay using one of the pins for the DO Module of my Revolution PI. I also need to have a way to power the same relay using a manual button. Here's a simplified diagram of what I'm trying to do: My question is: Does the DO Module have any built-in protections so the current from the button being pressed doesn't go inside the pin? Or do I need to do place a diode like this to avoid the current going in? Thank you for your help!

- Rodrigo