Keep in mind I'm using Construct Classic, not Construct2, so my angles and stuff may be different than yours. But basically what I did was make sure the angle is being checked whenever the turret is moving, or not moving, and then I assigned animations to every possible angle. Here's how:
Turret - Is moving
Turret: Angle >= 61
Turret: Angle <= 119 Turret: Set animation to "Down"
Turret: Angle >= 120
Turret: Angle <= 150 Turret: Set animation to "DownLeft"
Turret: Angle >= 151
Turret: Angle <= 209 Turret: Set animation to "Left"
And so forth until I'd covered all possible angles. Then I repeated for when the turret's not moving, and it seems to be working ok so far.
This is the link to what I've got: http://ppl.ug/gZdoYdSJfxc/. The turret is the player, you control it with up, down, left, and right. Press "e" to make it acquire target and fire. It should automatically rotate, with animations, towards the "enemies" (red x's).
But now I'm wondering if I can get some more help. As you can see from my example, I want the player to control the turret. And I want it to aim at enemies and fire, using the animations which I've provided, which seems to be working. However, I want the turret to stay angled towards the target, even when the player is moving the turret. For example, in top down shooters where you control where the player points using the mouse, but he can move freely without aiming all over the place. I want to accomplish that, but with the turret automatically finding targets and keeping aimed at them while the player moves. Any ideas?