Command to send data to the serial port freezes

Sorry for the translation of content from Google Translator
Lineup:
Device: PortServer® TS 8-port or 2-port (parameterised as realport)
OS: Red Hat Enterprise Linux Server release 6.4 (Santiago)
Driver: 40002086_W.src.rpm

Data exchange on the serial port is initialized and is working OK (communication is only one direction through the shell command echo “string”> / dev / tty …) but at some undefined point shell command freezes. Where could be the problem?

Recommend running dpa.dgrp to monitor the serial port signals to ensure OFC an IFC are not asserting signifying a buffer overflow.

Also recommend running a loopback test on the port(s) to ensure they are functional:

http://knowledge.digi.com/articles/Knowledge_Base_Article/How-to-Perform-Loopback-Testing-in-UNIX-and-Linux-Using-the-DPA-Interface