How do I use heavy/secondary weapons?

[FlyinJ]

It says I need to press X on the keyboard, or RB+LB on the controller to fire them... but it doesn't seem to do anything. On my starter ship, I currently have a REM III light weapon and a Ion Cannon heavy weapon. How do I fire the Ion Cannon? I'm assuming RMB/RB is firing the REM III, right? (it looks like a spray of green particles when I fire it)

[Tanvaras]

Make sure you have an enemy targeted as Heavy Weapons only fire on targeted enemies. But yes X and iirc controller buttons you mentioned(I dont use controller) launch the heavy weaps. You should see the weapon launch and fly to the target and detonate. Also note that they are restricted to firing arcs as light weapons. So if its on top of your ship make sure your nose down slighty etc to bring it to bare.

[FlyinJ]

How can I tell what part of the ship a weapon is mounted to?

[Geek]

This is showed on the ship menu, and the drydock.