Our cyclades-serial-client only supports emulating a serial port with 8 bits per byte (cs8). If the physical port is configured for something else when sercd starts, c-s-c will print an error:
cyclades-ser-cli /var/opt/thinlinc/sessions/astrand/2/dev/ttyS0: NOTICE: Opening /dev/pts/5 pseudo-tty
cyclades-ser-cli /var/opt/thinlinc/sessions/astrand/2/dev/ttyS0: ERR: Can't set termios : Invalid argument
However, if using the LD_PRELOAD library with an application that changes to cs8, things works.
For completeness, it might be nice to support cs7 etc someday. Currently, this is not possible due to limitations of ptys. See http://marc.info/?l=linux-serial&m=120612342110347&w=2.
Followup to comment #1: I was using the JavaComm library comm3.0_u1_linux.zip. One good thing is that several demo programs are included. For example, the "BlackBox" application looks interesting.
On the stupid side, it's necessary to enter all serial port paths into javax.comm.properties. Ie, this file must be personal, meaning that all users also needs to have a personal comm.jar, meaning that you have to fiddle with CLASSPATH...