Uploading of CRD files depends greatly on the cards you have. For example, you can use Carlson application to transfer the CRD files to the HP48 if you have SMI, TDS or Topcon cards. However, TDS Survey Link is the recommended application to be used for uploading data. The problem is I can't install Survey Link since it requires a Hardware Lock to function properly. Without the lock, nothing can be done. I do recommend checking the built-in HELP section for Survey Link to learn about the connection procedure for HP48.