There exist several possible .cdl files but it is likely that at least some of them are eligible to be exported or saved as PDF documents. For example Signlab, which uses .cld files for vector graphics, has a default support for PDF format and thus can perform CDL to PDF conversion.
Convert SignLab vector graphics to Adobe Portable document format.
We found one software available in the database for this conversion.
Microsoft Windows software - convert cdl to pdf on Windows
A professional software for signmakers
Convert from cdl 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.