I have a Solis Hybrid inverter, so I don’t know the particular details of your Deye other than reading the manual online.
Inverters connect to the battery BMS over the CAN port (which sometimes can include RS485 as well, used to talk with the battery).
There will also be an RS485 meter port. This goes to the power meter used to measure the grid import/export.
You will not get anything out of the meter port, so you need to look for a Modbus / Comms port. The Modbus protocol works as ‘master’ and ‘slave(s)’ with only one master that does all the talking, and one to many slaves that respond to the master read/write requests. For the meter port, the inverter is the master and the meter the slave. The inverter reads the meter, and will not respond itself to any read requests over that port.
For reading the inverter details, you need the computer to be the master and the inverter the slave. There appears to be a ‘Modbus’ port on your inverter.
Serial RS485 settings are most likely to default to 9600 baud, no parity, one stop bit. Slave ID should be set to ‘1’ (which is the most commonly used setting) and your inverter must be a Modbus Slave.
The manual suggests the RJ45 port pins are 1-B 2-A and also 7-A 8-B, which I have never seen before but does mean that you don’t have to worry about which way around the plug is! You are unlikely to need ground, and you may need terminating resistor(s) but only if you are getting occasional errors on the connection.
As always with Modbus, the A-B can be wrongly labelled [particularly on cheap USB adapters] so always try swapping them over. Always use a twisted pair from a cat cable.
USB adapters can work, but it is noted that these use various chip sets, some of which don’t work well/at all. If you have a long enough cable, try using the USB adapter in a Windows PC which is likely to have the necessary drivers, and you can easily find Modbus software that can be used to test the connection.
Whilst USB-RS485 adapters can work OK, the use of a Modbus TCP gateway can make it all easier. As long as you use an RS485-Ethernet adapter that is Modbus aware and can perform Modbus RTU to Modbus TCP translations, and you can get access to your LAN for the adapter location, Modbus TCP is easy to work with. Adapters usually have easy webpage configuration and helpful tools such as self-test and loopback-test.
I hope that has been of help to you. Modbus can be challenging as everything (settings, cable, adapter, software) has to be correct or nothing works.
