I have a solar inverter from Growatt (Model: MAX 70 KTL3 LV datasheet in attachment). I’m trying to read data from it using Modbus. For this, I’ve linked it to my laptop using an RS485 cable (with an USB-converter for my laptop’s USB port).

I’ve been having some trouble reading the parameters. I’ve done some troubleshooting and there are two things I need help with:

-Allegedly, I need to explicitly set the USB port I’m entering the USB-connector to as an RS485 port. This should be do-able in device manager. In demonstrations, I see a check box under the ‘port settings’ tab under the window that opens when clicking the COM-port in question. I, however, can’t find such a thing, also not under the ‘driver’ tab.


How should I be doing this?

-I’ve been told solar converters from this brand won’t give off any data if you don’t request it. The producer has given me some documentation with commands (attachement: Growatt Inverter Communication Command), but it’s badly translated from Chinese and I can’t understand them. Is anyone familiar with the commands written in this file and how I should enter them? Is there a specific type of software I need? How do I interpret them anyway?

 

Welcome to AAC.

One problem might be that the XR21B1411 chip explicitly supports RS485 and so it's driver would have an option to do the auto-switching necessary fir half-duplex while the CH340 chip you seem to be using does not have any particular RS485 support.

From the XR21B1411

From the CH340 datasheet:

So in the case of the XR21B1411 there is firmware that handles RS485 protocol at the hardware level, that checkbook sets configuration registers to enable it, while the CH340 needs to external software for that function.

This doesn't mean you can't use it, only the it won't have the checkbox in the driver. The RS485 function is somewhere else.

 

Welcome to AAC.

One problem might be that the XR21B1411 chip explicitly supports RS485 and so it's driver would have an option to do the auto-switching necessary fir half-duplex while the CH340 chip you seem to be using does not have any particular RS485 support.

From the XR21B1411
View attachment 274147
From the CH340 datasheet:
View attachment 274145
So in the case of the XR21B1411 there is firmware that handles RS485 protocol at the hardware level, that checkbook sets configuration registers to enable it, while the CH340 needs to external software for that function.

This doesn't mean you can't use it, only the it won't have the checkbox in the driver. The RS485 function is somewhere else.

Thanks for your response. Are you saying I specifically need software to allow RS485 communication with the CH340 I'm using, or could it also be hardware? I asked these questions on another forum and was told that there is such a thing as an RS485 driver chip, which this here USB converter seems to have https://www.hobbyelectronica.nl/product/max485-module-voor-rs485-seriele-communicatie-usb/ (this is not the specific converter I'm using, which I have no idea if it contains an RS485 driver chip).

 

Thanks for your response. Are you saying I specifically need software to allow RS485 communication with the CH340 I'm using, or could it also be hardware? I asked these questions on another forum and was told that there is such a thing as an RS485 driver chip, which this here USB converter seems to have https://www.hobbyelectronica.nl/product/max485-module-voor-rs485-seriele-communicatie-usb/ (this is not the specific converter I'm using, which I have no idea if it contains an RS485 driver chip).

What I am saying is that something has to be handling the RS485 protocol since the CH430 doesn't have the hardware support for half duplex built it. The XR21B1411 has such firmware, which is why there is a checkbox in the hardware driver configuration.

The device you linked uses the Max485 chip which is hardware designed to support RS485. It is used in typical UART to RS485 converters. The difference in that device is that it has both USB to UART and UART to RS485 converters together.

I suspect that you just need to buy something different to what you have.