1.) What cable do I need for connection between PC and DCULx:
There are 3 lines involved: Rx, Tx and Ground; nothing else is needed. Shouldn't be too difficult to figure out the correct connection. The pin layout of the serial line connector of the DCU can be found in part 4 (hardware) of the DCU documentation. (In case you don't have it, the documentation can be downloaded from <!-- m --><a class="postlink" href="http://www.fs-net.de">http://www.fs-net.de</a><!-- m --> (Support->Download).)
2.) What parameters must bes et to get connection working (Serial Port Set-up / Configuration, baud rate, etc.)
About the connection between PC and DCU-L3: a very simple way to test this is by the use of the provided terminal program. The parameters to set are: 19200bps, 8 data bits, 1 stop bit, no parity, no flow control. So open the connection (menu Action->Connect) and then power on the DCU. You should receive the two characters "&!" which indicate a correct selftest and power on sequence on the DCU, or probably a message about a missing definition file at address 80000, which is absolutely ok when the flash memory is empty. If you can't see anything, the connection DCU->PC is not yet correct.
Now you can check the other direction of the connection by typing the character '@' on your PC keyboard. If everything works, the DCU-L3 should immediatly answer with a version string. If this fails, then your connection PC->DCU does not work.
If both tests do work, the connection cable is set up correctly and download and everything else should also work.
F&S Support Team