As far as I know the chassis size can only be set through the web browser and RSLogix 5000. It's been some time since I have attempted to use the web browser because of java becoming unsupported. With RSLogix 5000, open the project that is referencing the pointIO. While offline, find the AENT in the IO tree on the left of the screen and right click to open properties. In the "General" tab of the properties, in the module definition box, click "Change". The pulldown will adjust the chassis size to your liking. After setting the correct chassis size, (number of modules plus AENT) click "Apply" and download project. If the processor is in run mode, it will switch to program mode. Go online with the processor after downloading the updated chassis size and right click the AENT again and open properties. Click the far right tab "Chassis Size" and click "Set Chassis Size In Module". You're done now.