Converting Modbus response using pymodbus

Question

I want to comunicate a PC with a smart meter which allows Modbus TCP communication, the PC will be the master and I just need read holding registers and show them in float format. I'm using python with pymodbus 2.2.0 My code is:

from pymodbus.client.sync import ModbusTcpClient

client = ModbusTcpClient('169.254.00.10')

result = client.read_holding_registers(1845,1,unit=0x01)
print('**************************************************************')
print(result)
client.close()

what I get is:

DEBUG:pymodbus.transaction:Current transaction state - IDLE
DEBUG:pymodbus.transaction:Running transaction 1
DEBUG:pymodbus.transaction:SEND: 0x0 0x1 0x0 0x0 0x0 0x6 0x1 0x3 0x7 0x35 0x0 0x1
DEBUG:pymodbus.client.sync:New Transaction state 'SENDING'
DEBUG:pymodbus.transaction:Changing transaction state from 'SENDING' to 'WAITING FOR REPLY'
DEBUG:pymodbus.transaction:Changing transaction state from 'WAITING FOR REPLY' to 'PROCESSING REPLY'
DEBUG:pymodbus.transaction:RECV: 0x0 0x1 0x0 0x0 0x0 0x5 0x1 0x3 0x2 0x6 0xc
DEBUG:pymodbus.framer.socket_framer:Processing: 0x0 0x1 0x0 0x0 0x0 0x5 0x1 0x3 0x2 0x6 0xc
DEBUG:pymodbus.factory:Factory Response[ReadHoldingRegistersResponse: 3]
DEBUG:pymodbus.transaction:Adding transaction 1
DEBUG:pymodbus.transaction:Getting transaction 1
DEBUG:pymodbus.transaction:Changing transaction state from 'PROCESSING REPLY' to 'TRANSACTION_COMPLETE'
**************************************************************
ReadRegisterResponse (1)

Do you know how to resolve it using pymodbus 2.2.0?

Answer 1

You have to extract the registers from your response, try this:

print(result.registers)

Or, if you want them one by one:

for reg in result:
    print(reg)

If you're not sure if your server is running, its IP or port it's a good idea to use a standalone tool to test, if you are on Windows you can use QModMaster to make sure your setting and mapping.

And note that with just one Modbus register you cannot get a float because Modbus register are 16 bits integers. If you want to get a float you need to read two registers.

If, on the other hand, you only want to verify your client-side code you can run this example on your computer simultaneously with your client code. Of course, you have to change the IP address on your script to localhost, the port to 5020 and the register number you're reading to a lower number (or increase the size of the server datastore). If you're on Windows you might need to disable or create a rule on your firewall.