#: 19134 S12/OS9/68000 (OSK)
    17-Oct-93  09:40:41
Sb: #OS9 Serial Port Problem
Fm: Bob Rea 72733,250
To: All

I am fighting a nasty problem in OS9 with a serial port (Matrix SI02)
transferring binary data.  Our code (device driver and application) works
perfectly on the test bench with a driver simulating the other system we are
exchanging data with.  In the field, however, the process is killed with a
signal 3 within 3 minutes of connecting the systems together.  And we don't
receive the heartbeat message from the other system that happens every 3
seconds.

We put a data monitor on the other system and it is behaving exactly as
specified and exactly as the simulation code we have.  We can detect no
extraneous data bytes in the information stream.

The symptoms act as though the buffer in the device driver in over- flowing.
That will cause a signal 3 to be sent killing our application and the 3 minutes
is just about what it takes to fill the buffer given it's size and data
transfer rate.  The question is: What could possibly be happening to work
perfectly on the test bench and not at all out in Nebraska (we unfortunately
are in Columbus, Ohio)?

The first thing to suspect is a hardware problem, but that does not explain why
no data is reaching the application.  The overflow could be caused by a bad
cable that is negating RTS/CTS (XON/XOFF doesn't work with our binary transfer
stream).  But it is hard to imagine a hardware problem that inhibits the
transfer of data from the device driver to the application.  When we first
installed the system, it did work correctly.... so we know it can work.

If anyone has fought through this problem and can help point me in the right
direction, it would be a great help.

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