Adjust Scanning Angle for RTX Lidar

Hi, I wanted to ask how to adjust the scanning angle for a RTX Lidar Sensor. I want to simulate a sensor with a scanning angle of 275°. So I adjusted the Start- and Endazimuth in the lidar config file to 0 and 275. When I create the lidar with the corresponding config file and start the simulation I have still a full scan with 360°
I have put some cubes around my sensor to see if it scans the full circle or only the 275° (see image below)
What can I do to reduce the scanning angle to 275°?