[CentOS] Serial Communication

Sat Dec 19 12:24:05 UTC 2015
Chris Olson <chris_e_olson at yahoo.com>

Many years ago, we began scrapping the RTOS approach for some
of our timing-critical applications.  Our first applications
were based on Solaris real-time extensions and served well us
well for many years.  Then came the era of shaky support for
Intel Solaris and we moved many applications to Linux.  There
appeared to be no actual need for special real-time features
with a good Linux distribution kernel and a GHz processors.

One of our most productive applications involves special test
equipment computers that drive high speed serial ports.  The
original development of these systems had the "added benefit"
of helping us to learn udev rules.  The serial communication
is very flexible and most of it is script driven.  A current
need to update computing platforms is driving script review.

There appears to be a bit of variety in outputs to the serial
drivers.  The echo of a string with redirection to the serial
driver, cat of a file with redirection to the serial driver
and dd of=/dev/.... are methods used at various places in the
scripts.  It is not at all clear what drove the choice of the
output method at various points in the application. In addition,
changing the method of output has not succeeded in breaking most
of the applications.

Is there some fundamental difference between these methods of
output to the driver that might trip us up as we simplify the
scripts and port to new computer platforms?

Thanks in advance for any assistance.