Can't read data, help please. about srne-solar-charge-controller-monitor

[Shadow-Genesis]

Thank you, and wow that was fast.

[cole8888]

Hi, sorry for the delayed response. I've been able to reproduce the problem on my PI also and I'll try to have a fix for it soon.

[cole8888]

The correct setup is Raspberry pi GPIO14 goes to MAX3232 TX and GPIO15 goes to RX

While trying to reproduce it I had the wires backwards and got the behavior you mentioned. After flipping them to be correct I was able to read data. Also what python/pymodbus version are you using?

[cole8888]

I just double checked the wiring photos in that directory and they are correct.

This one is probably the easiest to compare against:
https://github.com/cole8888/SRNE-Solar-Charge-Controller-Monitor/blob/main/RaspberryPi-Examples/RaspberryPi-Top-View.jpg

[Shadow-Genesis]

I'm using a USB connecter, and I did check and redo my wires. Pin 1 to my RX and pin 2 to my TX and pins 3 & 4 to ground. Pins 5 & 6 are power and not connected.

I just tried flipping the tx and rx to make sure and still the same.

FYI: Pins 5 & 6 give off battery voltage.

[Shadow-Genesis]

So I got a bit of an update. I have for my pc the Solar Station Monitor software. With it I can connect if I set the device ID to 255. Still not working with the python script. Any ideas?

[cole8888]

Address 255 is a special address that all charge controllers respond to no matter what their current address is.

Your controller must have a different address than mine. Ran into a similar thing with the Arduino versions and I fixed it there by forcing address 255, but I didn't realize the python version would also have this problem.

Try replacing the line with read_holding_registers with this:
response = modbus.read_holding_registers(256, 35, unit=1, slave=255)

[Shadow-Genesis]

So adding the "slave" parameters fixed it. I would like to note that the code works without the "unit" parameters and that the "slave" needs to be your device ID.

response = modbus.read_holding_registers(256, 35, slave=1)

Thank you for your help, hope this helps others.

[cole8888]

@Shadow-Genesis Just wondering, did this work when you set slave to 255 instead of 1? If it worked with 255 I'll update the program since it should work for all controllers.

[Shadow-Genesis]

Both. My device is ID 1. And from what I read in the PDF that talks about how data is sent and received, 255 is a device ID that all respond to. Mostly for use with bluetooth adapters and remote displays. So in short from what I read, the device ID 255 is a plug and play ID

[cole8888]

Ok, I'll update the script to use 255, should prevent issues in the future. Thanks!

[Shadow-Genesis]

I had been making since last night a python class that would handle the SRNE data, makes it cleaner for me. I just got a bit of code I think you may want to add.

deviceID=None response = self.modbus.read_holding_registers(26, 1, slave=255) deviceID = response.registers[0] response = self.modbus.read_holding_registers(256, 35, slave=deviceID)

its just a little auto device ID. I do not think it would work with more then one slave connected, but for one it should be fine