You might be able to catch DTR dropping.
APRO Developer's Guide has a section on installing SAPI (available through Files | Docs). It's been a lifetime ago since I worked with it. The install order is important if you have both SAPI4 and SAPI5 installed together. I recall that SAPI4 had to be installed first. If SAPI5 was already installed change your path so the SAPI4 folders are first. Also, the SAPI engines need to be installed as admin.