Modbus cant read data from epever tracer 1210a to raspberry - python-3.x

Question

i want to make a monitoring program for tracer
i use rs485 usb converter to connect epever tracer1210a to raspberry pi 3 model b
from pymodbus.client.sync import ModbusSerialClient as ModbusClient
client = ModbusClient(method = 'rtu', port = '/dev/ttyACM0', baudrate = 115200)
client.connect()
print( client)
result = client.read_input_registers(0x3100,6,unit=1)
print (result)
solarVoltage = float(result.registers[0] /100.0)
solarCurrent = float(result.registers[1] /100.0)
batteryVoltage = float(result.registers[4] /100.0)
chargeCurrent = float(result.registers[5] /100.0)
print("solar voltage : ",solarVoltage)
print("solar current : ",solarCurrent)
print("battery volatage : ",batteryVoltage)
print("charge current : ",chargeCurrent)
client.close()
and i get error like this:
ModbusSerialClient(rtu baud[115200])
Modbus Error: [Input/Output] Modbus Error: [Invalid Message] Incomplete message received, expected at least 2 bytes (0 received)
Traceback (most recent call last):
File "yutub.py", line 9, in
solarVoltage = float(result.registers[0] /100.0)
AttributeError: 'ModbusIOException' object has no attribute 'registers'
please help me to fix this problem

Answer 1

I had faced the same problem.
Follow the below steps to fix the issue:
git clone https://github.com/kasbert/epsolar-tracer/tree/master/xr_usb_serial_common-1a
Follow the installation steps from Readme.
You might face problem when you execute make. In such case do sudo apt-get install linux-headers.
Check that the USB UART is detected by the system
lsusb
Check that the CDC-ACM driver was not installed for the Exar USB UART
ls /dev/tty*
To remove the CDC-ACM driver and install the driver:
sudo rmmod cdc-acm
sudo modprobe -r usbserial
sudo modprobe usbserial
sudo insmod ./xr_usb_serial_common.ko
After this when you do ls /dev/tty* you will see /dev/ttyXRUSB0. This means the driver is installed and you are in good shape.
Change the port in your code to '/dev/ttyXRUSB0'.
See the output image
After you restart the PI you might not see the ttyXRUSB0 instead you will see ttyACM0. In such case execute sudo echo blacklist cdc-acm > /etc/modprobe.d/blacklist-cdc-acm.conf. If PI does not allow you to execute then create the file in the path and write blacklist cdc-acm.
Reboot and verify if ttyACM0 is still displayed in ls /dev/tty*.