CaptionView is unmaintained software (parent company has apparently folded) for use with modified Alpha LED signs. I encountered it among Philadelphia theatres using it to caption performances.

The software and signs were sold to several theatres in the early 2000’s. The signs still work, CaptionView still installs on at least up to Windows 10 (and probably 11). The USB serial cable used to connect the sign’s RS-232 cable, has recently become unsupported in Windows. By replacing this cable, the system are able to work again.

Here’s info that I’ve assembled surrounding CaptionView and these particular Alpha LED signs. There is info on the installer, the cable and drivers, the signs and some tips for CaptionView:
CaptionView/Alpha Sign Info – Google Docs