RS485 Display, 0.56 Inch 4 Digit LED Display RS485 Serial Port Tester Communication MODBUS-RTU/ASCII Protocol 30mA DC 7~36V

No manufacturer documentation online, a hobbyist has published information that is helpful but incomplete, and having gotten the device to work once it has repeatedly lost its settings and finally will not accept new settings. It's not worth messing with and I regret the purchase.

I spent days trying to communicate this display with Modbus RTU. Poor documentation. Finally, browsing in other websites I found some details about modbus registers to be pointed to (40001 to 40007). The device doesn't respond to Modbus requests, it only accepts commands to change the value displayed, decimal point, brightness and other setting modifications. The device has a jumper inside which I have not idea what is for.

Arrived with no documentation at all, I searched the internet, and found nothing, I need the registers and their purposes to be able to know what so send to the unit over RS485.