I just started working with my new (to me) EQ6-R and wanted to report some successes I've had with various PC connection options. I'm running a v5 SynScan HC with firmware version 4.39.04. Scope-side computer is a minisforum SBC dual booting Win 10 and Ubuntu Mate. I don't know yet if I'll run the mount entirely via EQMOD like many other CNers, or if I would rather keep the HC involved and use that for initial alignment. I wanted to keep both options open.
1) PC direct to mount via HC port on the mount and this $15 USB to TTL serial RJ45 cable. Works with EQMOD driver in both Windows and Ubuntu (indi). No clunky DB9 serial adapters needed.
2) PC to HC serial port via a $7 FTDI cable and a $1 RJ12 connector which I hand-crimped to it. I think this is the same as what Eric Seavey described, and it's also exactly equivalent to Shoestring's $43 usb2eq5 cable. Both Windows and Ubuntu Mate handled the FTDI driver automatically.
3) PC to HC USB-2B port works well with SkyWatcher ASCOM driver in Windows. Windows was initially unable to identify a driver for the USB-to-serial chipset built into the v5 HC, but this was fixed easily in device manager by selecting "Search automatically for updated driver", without needing to manually download and install the chipset driver. No luck yet in linux.. may need to manually compile and install the chipset driver.
I did not use the "PC Direct" utility on the HC for any of these configurations.
@dilipsharan, in my understanding, if you're connecting PC to HC then you should use the SkyWatcher ASCOM driver, not EQMOD. Use EQMOD if you're bypassing the HC by connecting directly to the mount.