System Generator automatically creates a new hardware co-simulation block once it has finished compiling your design into an FPGA bitstream. It also creates a Simulink library to store the hardware co-simulation block. At this point, you can copy the block out of the library and use it in your System Generator design like any other Simulink or System Generator blocks.
The hardware co-simulation block assumes the external interface of the model or Subsystem from which it is derived. The port names on the hardware co-simulation block match the ports names on the original Subsystem. The port types and rates also match the original design.
Hardware co-simulation blocks are used in a Simulink design the same way other blocks are used. During simulation, a hardware co-simulation block interacts with the underlying FPGA board, automating tasks such as device configuration, data transfers, and clocking. A hardware co-simulation block consumes and produces the same types of signals that other System Generator blocks use. When a value is written to one of the block's input ports, the block sends the corresponding data to the appropriate location in hardware. Similarly, the block retrieves data from hardware when there is an event on an output port.
hardware co-simulation blocks may be driven by Xilinx® fixed-point signal types, Simulink fixed-point signal types, or Simulink doubles. Output ports assume a signal type that is appropriate for the block they drive. If an output port connects to a System Generator block, the output port produces a Xilinx® fixed-point signal. Alternatively, the port produces a Simulink data type when the port drives a Simulink block directly.
Like other System Generator blocks, hardware co-simulation blocks provide parameter dialog boxes that allow them to be configured with different settings. The parameters that a hardware co-simulation block provides depend on the FPGA board the block is implemented for (i.e. different FPGA boards provide their own customized hardware co-simulation blocks).