Downloading firmware over the serial cable can be tricky, this document gives further information on the required equipment and settings for the serial connection and the system.
The following are a list of potential solutions when connecting to the CCU or WCCU to upgrade the system firmware:
Cable from the PC to the CCU/WCCU must be a 9 pin DB9 null cable. A three pin only cable (2,3,5) will not work.
Check your serial comm port setting on your pc and compare it to the comm port setting on the Download and Licensing Tool (DLT). Communication port settings must match.
Make sure the switch settings (S500) for the CCU/WCCU are set to default (Full) for RS232 port 1. S500 switch 1=On, 2=Off, 3=On, 4=On, (5-8 are set for RS232 port 2).
If the system is communicating on the RS232 port and the CCU/WCCU is freezing up (failing) during a download, then try the following switch setting.
To force a firmware download to the CCU/WCCU, set switch S600-8 = On. This will put the CCU/WCCU in boot mode and enables a new firmware upload (in case a download failed). Once the firmware download is complete, change the switch S600-8 to Off.
Note: Refer to the manual (IUI_DCN_en.pdf) for version 3.1x for details where to find the DIP switches mentione din this artcile. The manual is found on the DCN-NG software ISO.