Hi,
I'm new to using INDI and somehow can't manage to connect via CDC (Client) -> Indi Server -> Indi Driver (EQmod or Synscan) to my mount.

I'm running Mac OS 10.13, CDC 4.0-3575, Indi Server 2.7.0 (1.7.0) and tried EQMod Mount (0.3) and Orion Atlas (1.0)
As HW I have the Orion Atlas EQ-G GoTo, Shoestring's EQDIR and Prolific Technology USB to Serial with installed PL2303 v1.6.1 driver.

HW / Cables are OK as I tried EQMac -> USB2Serial -> EQDIR -> Atlas Mount successfully

My understanding:
To use EQMod driver I connect USB2Serial -> EQDIR -> Atlas Mount directly
To use Synscan driver I connect USB2Serial -> Synscan HC -> Mount

EQMod:
When adding EQMod to the Indi Server it shows yellow in the INDI server app and is not visible in CDC after hitting "Connect and get server list".

SynScan:
Shows green in INDI Server and selectable in CDC. Power up mount and initialize / do alignment via HC. Select PC Direct Mode (also tried w/o this step) and connect Mac via USB2Serial and SynScan Cable to HC. Then I open the INDI gui panel and entered as port /dev/cu.usbserial (alternatively tried with /dev/tty.usbserial as well) and always receive (with debug information active):

CONNECTION CONNECT=ON
[DEBUG] Connecting to /dev/cu.usbserial
[DEBUG] Port FD 9
[DEBUG] Connection successful, attempting handshake...
[INFO] Synscan Mount not responding
[DEBUG] Handshake failed.
[WARNING] Communication with /dev/cu.usbserial @ 9600 failed. Starting Auto Search...
[DEBUG] Trying connection to /dev/cu.Bluetooth-Incoming-Port @ 9600 ...
[DEBUG] Connecting to /dev/cu.Bluetooth-Incoming-Port
[DEBUG] Port FD 10
[DEBUG] Connection successful, attempting handshake...
[INFO] Synscan Mount not responding
[DEBUG] Handshake failed.

If I try to connect a second time w/o changing anything I receive:

CONNECTION CONNECT=ON
[DEBUG] Connecting to /dev/cu.Bluetooth-Incoming-Port
[ERROR] Failed to connect to port (/dev/cu.Bluetooth-Incoming-Port). Error: Port failure Error: Resource busy. Check if device is connected to this port.
[WARNING] Communication with /dev/cu.Bluetooth-Incoming-Port @ 9600 failed. Starting Auto Search...
[DEBUG] Trying connection to /dev/cu.Bluetooth-Incoming-Port @ 9600 ...
[DEBUG] Connecting to /dev/cu.Bluetooth-Incoming-Port
[ERROR] Failed to connect to port (/dev/cu.Bluetooth-Incoming-Port). Error: Port failure Error: Resource busy. Check if device is connected to this port.

Now it is not even trying to connect to /dev/cu.usbserial

What am I doing wrong?

Thanks for you help,
David