title: Modbus cant read data from epever tracer 1210a to raspberry
body: <p>i want to make a monitoring program for tracer</p>
  
  <p>i use rs485 usb converter to connect epever tracer1210a to raspberry pi 3 model b</p>
  
  <pre><code>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()
  </code></pre>
  
  <p>and i get error like this:</p>
  
  <p>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'</p>
  
  <p>please help me to fix this problem</p>