The hardware requirements for the Add-On vary based on the selected hardware configuration. Each configuration details a different IO Count, FPGA Size, and Modeling Capabilities.Unless stated otherwise, there are no restrictions on the NI PXI chassis and controller models to be used with each supported configuration. Since every application has a unique set of requirements and may require additional hardware (ex. DAQ, XNET, etc), the chassis and controller should be selected on a case-by-case basis. For most hardware-in-the-loop applications, OPAL-RT recommends the following hardware.