Okay, I solved. I have used total_frames global variable. The code below:

Code:
function d_ates_et()
{
	proc_kill(4);
	while(my.d_saglik > 0)
	{
			if ((total_frames % 80) == 1) // fire a bullet each second
			{
				vec_for_vertex(temp_d, my, 240);
				ent_create(mermi_mdl, temp_d, mermi_hareket2);
				snd_play(mermi_wav2, 100, 0);
			}
		wait(1);
	}
}