Hello.
For reference if someone faces the same error in the future (or if Citect dev team have time to improve citect to handle this in a better way)
After adding a new MODNET device manually to a running system, When starting the runtime I got "Error / Cannot find serial drivers / OK" message followed by "Error / Driver MODNET not initialized / Do you want to shutdown now? / Yes/No".
The MODNET is an ethernet driver and I had no serial driver, so the message about serial drivers was strange.
The problem was the IOServer name on the boards and ports had a misspelling. That wasn't a problem before as all the other devices were OFSOPC devices, and have a port and a board with the same misspelling and work well.
Do add the new device I copy one existing port, so I copy the misspelling. And it took me some to figure out, as I made a copy of something working well.
If you use New Device Wizard this will never happen, but for others it may happen.
To development team: the compiler could check if the IOServer name in boards and ports exists on IOServers and give proper error/warning messege.
Regards