Athena xPC Target Serial Ports COM3 and COM4 not working

Hi,

Can't get COM3 and COM4 working on Athena SBC. Used the mainboard/baseboard FIFO serial blocks to communicate using COM2 successfully. However, changing it to COM3 and COM4 with the correct port addresses and IRQ numbers, data can be received, but not sent.

Because data was received successfully, the configuration must be correct. Therefore, I believe that the simulink block (serial FIFO block) is not compatible with COM3 and COM4.

COM1 and COM2 are part of the standard chipset, while COM3 and COM4 use a separate serial driver Exar 16C2850 dual UART. Has anybody else had this problem? Or is using COM3 and COM4 on Athena not officially supported by xPC Target.

Ronald