As I want to use Helicon Remote not only with focus bracketing but with a linear rail system I got the idea for doing an open source project on Github:
Based on cheap RP2040 Raspberry Pico board which has USB device/host integrated
Trinamic TMC2209 driver chip
So I think the best solution is to emulate the Trinamic PANdrive system which uses TMCL commands.
I hooked up a serial terminal to see what Helicon Remote sends, but those weren't the commands I would expect as those are not documented.
So what is Helicon Remote actually sending and expecting to recognize it as a genuine Trinamic PANdrive?
We don't use any undocumented commands, we only have the publicly available documentation as reference.
What you've seen in the terminal could be the commands to detect Wemacro or Stackshot3X. Your firmware will need to gracefully discard these unrecognized sequences.
The TMCM-1141 controller is not deprecated, as far as I know. Which device are you trying to emulate? Are you presenting your device as a virtual COM port or as FTDI interface? In all cases dynamic detection is used via communicating with the device, as VID+PID-based detection is not possible.