I am working on a project that involves a Solar Charge Controller. The device ships with an Ethernet RS-485 communication interface as well as a RS-485 to USB cable, which is said to be able to communicate with a PC using proprietary Windows based software (and driver, I think).
What I want to be able to do is to communicate (or at least read from) the charge controller from a Raspberry Pi.
This person has proved that it can be done (see link). But I notice that he describes using a (different) RS-485 to USB converter and splicing from the Ethernet cable to the converter, rather than using the converter cable that ships with the charge controller.
Simply using the provided USB converter cable is not working for me right now with the Pi.
So my question(s):
Is it necessary to do the ethernet cable splicing as indicated in the above link, or should I simply be able to use the provided USB cable?
Is it likely that the shipped cable is configured differently or do I simply have no way of knowing that (short of dissecting the cable)?
Note that this Hackster project does something similar with splicing an ethernet cable to a UART breakout module.
Best Answer
If you can find drivers for the R Pi then you can use the converter. I'd start by finding out what chip is in the propriety RS485 to USB, they might have a linux driver.
You will need a pinout and find the voltage, if you have an oscilloscope, it should be easy to find the pins that carry the RS485 and if they are using any additional pins for signaling (some RS485 converters also have GPIO's). By the looks of the webpage, they are only using the two differential pins and you could use any RS485 converter that is compatible with the voltage (which is probably 5V or 3.3V). Make sure the RS485 converter is compatable and find the two data pins and you should be able to roll your own.