@geehalel: I finally succeeded in building your modification of the skywatcherAPI into my system (don´t ask why it took so long...). Surprisingly, my mount still refuses to connect. The handshake still seems to fail at or after the "isDCMotor" routine. Here is the output of the logfile:
[2021-01-28T15:15:10.954 W. Europe Standard Time DEBG ][ org.kde.kstars.indi] - Skywatcher Alt-Az : "[DEBUG] Toggle Debug Level -- Scope Verbose "
[2021-01-28T15:15:22.107 W. Europe Standard Time INFO ][ org.kde.kstars.indi] - Skywatcher Alt-Az : "[INFO] Scan complete. Found 1 port(s). "
[2021-01-28T15:15:26.432 W. Europe Standard Time DEBG ][ org.kde.kstars.indi] - Skywatcher Alt-Az : "[DEBUG] ProcessTextProperties - name(DEVICE_PORT) "
[2021-01-28T15:15:27.616 W. Europe Standard Time DEBG ][ org.kde.kstars.indi] - Skywatcher Alt-Az : "[DEBUG] ProcessTextProperties - name(DEVICE_PORT) "
[2021-01-28T15:15:34.933 W. Europe Standard Time DEBG ][ org.kde.kstars.indi] - Skywatcher Alt-Az : "[DEBUG] Connecting to /dev/ttyUSB0 @ 115200 "
[2021-01-28T15:15:34.985 W. Europe Standard Time DEBG ][ org.kde.kstars.indi] - Skywatcher Alt-Az : "[DEBUG] Port FD 3 "
[2021-01-28T15:15:34.997 W. Europe Standard Time DEBG ][ org.kde.kstars.indi] - Skywatcher Alt-Az : "[DEBUG] Connection successful, attempting handshake... "
[2021-01-28T15:15:35.008 W. Europe Standard Time DEBG ][ org.kde.kstars.indi] - Skywatcher Alt-Az : "[SCOPE] SkywatcherAPIMount::Handshake "
[2021-01-28T15:15:35.019 W. Europe Standard Time DEBG ][ org.kde.kstars.indi] - Skywatcher Alt-Az : "[SCOPE] InitMount "
[2021-01-28T15:15:35.030 W. Europe Standard Time DEBG ][ org.kde.kstars.indi] - Skywatcher Alt-Az : "[SCOPE] CheckIfDCMotor "
[2021-01-28T15:15:36.948 W. Europe Standard Time DEBG ][ org.kde.kstars.indi] - Skywatcher Alt-Az : "[SCOPE] SkywatcherAPIMount::Handshake - Result: 0 "
[2021-01-28T15:15:37.000 W. Europe Standard Time DEBG ][ org.kde.kstars.indi] - Skywatcher Alt-Az : "[DEBUG] Handshake failed. "
[2021-01-28T15:15:37.054 W. Europe Standard Time DEBG ][ org.kde.kstars.ekos] - "Skywatcher Alt-Az" is disconnected.
[2021-01-28T15:15:37.066 W. Europe Standard Time INFO ][ org.kde.kstars.ekos] - "Skywatcher Alt-Az is disconnected."

Read More...