SingLab is a popular layout and production software and it also supports graphics documents made in Adobe illustrator (.ai) and hence your best and most likely also only option for conversion of AI to CDL. It doesn't seem to possible to generate this type of .cdl files using any other 3rd party software.
Convert Adobe Illustrator graphics file to SignLab vector graphics.
We found one software available in the database for this conversion.
Microsoft Windows software - convert ai to cdl on Windows
A professional software for signmakers
Convert from ai file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.