Turret rotation issue

Hy guys, i'm a begginer in Construct 2, and I really need one little help

I'm doing a game with simple tank, and a objective is to destroy a building.

I made point n click movement for tank, fireing bullets, turret is pined to tank, turret have rottate up and down, when bullet touch building bullet is destroyed, and make a some force to building etc...

But I have little problem, in turret rotation How can I make that left side of turret have fix position to tank, and when I press up or down - only right side of turret have rotate?

In picture you can see my problem

I'm using free edition of C2.

Thanks!

Pin to "PostoljeTopa" position only ?

This condition is already set to game. "PostoljeTopa" is a tank base, "Top" is turret of tank.

Now when I press up or down - turret rotates arround his center, but I want that turret rotates arround left side of turret.

Here is another picture of this problem

Here is example when I shoot "down".

First picture is like I want to be, left side of turret pin to tank base, so when I rottate turret, it rotates arround left side of turret, and pined to tank base.

Second picture is what is problem now.

set origin point... (For "Top")

I will try with this, tnx!

It works, tnx !!

Does anyone knows how to add a compare value that compares something like "is the mouse cursor in front of turret"?

With this I will avoid that turret can not fire behind himself , just in front of his angle.

Like: mouse.X >= turret toward angle.

I was look at every example and look in manual, but can't figured out.