JUART / nios2-terminal bandwidth limit

We are trying to use a part of a StratixII as a RS232 server :

- 6 uarts, at 9600 baud, are connected to the outside world : actual computers

- Data from the 6 uarts are "routed" by a NIOS2 ( at 25Mhz ) to 5 juarts

- Data is then displayed by the 6 nios2-terminals ( remote access )

To test the above, a 2nd NIOS2 is configured to generate data to the 6 uarts ( no reverse traffic yet )

The above works OK only if the 2nd NIOS2 is throttled to less than 200 char/sec. http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/blink.gif

The 1st NIOS2, which routes the data between the uarts and juarts doesn&#39;t seem to be the major problem. There are occassional missing char when the char rate is raised. The more disdurbing problem is the disappearance of all the niso2-terminals http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/mad.gif , with the following error msg :

nios2-terminal: exiting due to I/O error communicating with target

Note :

Failure of the nios2-terminals does not affect the operation in the StratixII.

As soon as the nios2-terminals are restarted, data is display, and nios2-terminals vanishes, .... http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/sad.gif

This symtum remains with the following variations on the routing-NIOS2 :

- for both the reduce/non-reduced drivers

- use POSIX open/read/write and use the direct I/O ( the IORD & IOWR macros ).

- use POSIX open/read/write one-byte-at a time Vs multBytes read/write ( improves through put )

- for all 6 uarts/juarts Vs only one uart/juart

- run nios2-terminal on WinXP and Linux. ( The WinXP nios2-terminals takes a bit more time to crash )

My gut feel is that there is a bandwidth limit on the juart ( through the JTAG/USBBlaster ), and the USBBlaster/HostDriver failed to handle overflow, and cause the JTAG port to be closed.

Your insights to improve / explain the implementation is much apprecipated.

http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/ph34r.gif