xPC Target

Host and Target PC Communication

If the host PC and target PC are connected using serial communication, one COM port on the target PC is dedicated for communication with the host PC. You cannot use this COM port in your block diagram as an I/O device.

For example, if the target PC uses COM1 for the communication with the host PC, COM1 cannot be used by your block diagram. If you try to use COM1 as an I/O device in your block diagram, an error message is displayed. The error message appears when you attempt to build and download the target application. In this example, it would be necessary for you to use COM2 as an I/O device in your block diagram.

If you are using TCP/IP as your host PC to target PC communications protocol, then you can use any of the COM ports for RS-232 I/O.

Note    COM1 and COM3 share interrupt line 4. Similarly, COM2 and COM4 share interrupt line 3. To provide maximum performance, the COM port interrupt line on your target PC used for serial communication is disabled while real-time tasks that include RS-232 blocks are executing. This also means that when COM1 is disabled, COM3 is also disabled since they both share the same interrupt line. For this case, you would have to use either COM2 or COM4 as your RS-232 I/O device.

MATLAB Message Structures for RS-232

RS-232 Synchronous Mode