I’ve just worked on JTX1 serial before so I’ve seen it. The schematic also shows J17 which can be traced to the camera.
I don’t use windows (I’d have to lose DHCP via host and other things would be lost if I did that), but serial port issues often resolve around one of these symptoms (regardless of host o/s):
- No data
- Corrupted data
- Intermittent data
Corrupted data tends to be invalid TX/RX speed mixes, but other settings correct. No data also tends to be invalid TX/RX speed mixes which are very far from correct, though sometimes other settings are an issue. Intermittent data tends to be operating at the edge of valid signals, especially with software flow control (hardware flow control allows pushing things much further).
In the case of being at the edge of valid signals, I might suspect hardware flow control is not enabled; or for one direction of a pipe not working perhaps CTS/DTS flow control is enabled on only side of the pipe (the two end points must match for all settings). I suspect data rate, bits, and parity are correct, but perhaps you still need to set CTS/DTS at both ends and currently only one end is set that way; if both are software flow control, then it implies signal timing is better in one direction than the other.