The usual 115,200 baud, 8 bits no parity should work OK.
Do you still get those invalid characters during the startup after you reboot the DVR?
Do you still have web GUI access to the Hikvision DS-7608HI-ST ?
If so - are there any settings for the serial interface?
I'm wondering if there are any settings choices for the RS485 and serial console.
Can you say more exactly which adapter you use?
Perhaps it is the driver of the adapter.
Try a different terminal program.
It's possible (it happens on the Huisun Mini PTZ cameras) that some program in the firmware takes over and changes the settings of the UART.Do you still get those invalid characters during the startup after you reboot the DVR?
@alastairstevenson
this Device has no SUB D for RS232
@aryjrbnu
You can show a picture where you pick up the UART on the Mainboard
You are sure that it is the right connection, you can unfortunately recognize in the picture nothing since it has bad quality. I have here a DS-7604HI-ST / A which has 2 connections. One is near the realtek chips, the other is near intersil chip. The Intersil chip is the right one. It can also be that the connection is not equipped with a base. I had recently a camera on the table, since the connection was missing on the board, it was not soldered.
View attachment 14542
I use this UART with Win 10, and no Problems on CAM´S an Recorders.
https://www.sparkfun.com/products/12731
My suggestion would be, you try it times with another Terminal Programm and another UART. Otherwise I have also no idea. I also had times cryptic characters on a camera, which was however corrected after I had exchanged the cable of the camera. There was a short circuit at the Network plug.