Help Wanted in converting hexadecimal numbers from Modbus to Floating point numbers

[JvW]

Sorry for my bad english 

Help Wanted in converting hexadecimal numbers from Modbus to Floating point numbers.

I have a Eastron sdm630 kwh meter and I would like tricks the information that I can use on a website. 

In particular, the volt, watt and total watts are important. 

With python modbus rtu I get the input registers from the Eastron. 

Maybe it goes all wrong here, and I start wrong, it is not entirely clear to me also. 

I can not get it together to convert them into readable floating points. 

How do I get it done, for example, the output 17250, 43125, convert to volts. 

17250, 43125, according to the display +/- 226.4 volts. 

The Eastron uses 32 bit registers composed of 2 x 16-bit registers. 

That means my knowledge that the input voltage consists of register 0 and 1. 

In the Annex, the modbus explained. (link) 

Can someone please help me further with the right python script rules? 

I already searched more than 20 hours on the Internet and tested several examples, nothing really helps me further. 

Thanks! 

The following test script I get the data on the screen: 

#! / usr / bin / env python 

from pymodbus.client.sync import ModbusSerialClient axis ModbusClient 

import logging 

logging.basicConfig () 

log = logging.getLogger () 

# log.setLevel (logging.DEBUG) 

client = ModbusClient (method = 'rtu', port = '/ dev / ttyUSB0', baudrate = 9600, timeout = 1) 

client.connect () 

rr = client.read_input_registers (0, count = 10) #for debugging 

print rr.registers 

client.close () 

output: 

#python ./test.py 

[17250, 43125, 17250, 40548, 17250, 61852, 0, 0, 0, 0]

[Galen Collins]

Here you go: http://pymodbus.readthedocs.org/en/latest/examples/modbus-payload.html

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[JvW]

Thx, 

I go and test it, the script use TCP I use serial but I can change that part.

let you now if it work's.

Gr,

Jeroen

[JvW]

Bashwork,

I fix it thanx to your imput.

I now get the correct output 228.710876465 (volt) (that's the same as on the display of my KW/H meter.

I have to change the script from Endian to Big, and make some other changes to get my results.

Thx for your help!

Here is my script:

#!/usr/bin/env python

#---------------------------------------------------------------------------# 

# loading pymodbus modules

#---------------------------------------------------------------------------# 

from pymodbus.constants import Endian

from pymodbus.payload import BinaryPayloadDecoder

from pymodbus.payload import BinaryPayloadBuilder

from pymodbus.client.sync import ModbusSerialClient as ModbusClient

#---------------------------------------------------------------------------# 

# client logging

#---------------------------------------------------------------------------# 

import logging

logging.basicConfig()

log = logging.getLogger()

log.setLevel(logging.INFO)

#---------------------------------------------------------------------------# 

# Connect info KW/H meter

#---------------------------------------------------------------------------# 

client = ModbusClient(method='rtu', port='/dev/ttyUSB0', baudrate=9600, timeout=1)

client.connect()

#---------------------------------------------------------------------------# 

# 

#---------------------------------------------------------------------------# 

builder = BinaryPayloadBuilder(endian=Endian.Big)

builder.add_string('abcdefgh')

builder.add_32bit_float(22.34)

builder.add_16bit_uint(0x1234)

builder.add_8bit_int(0x12)

builder.add_bits([0,1,0,1,1,0,1,0])

payload = builder.build()

address = 0x01

result  = client.write_registers(address, payload, skip_encode=True)

#---------------------------------------------------------------------------# 

# Read data and convert to float and creating output files

#---------------------------------------------------------------------------# 

result  = client.read_input_registers(0x00, 2)

decoder = BinaryPayloadDecoder.fromRegisters(result.registers, endian=Endian.Big)

volt = open("volt.txt", "w")

print >>volt, decoder.decode_32bit_float(),

result  = client.read_input_registers(0x34, 2)

decoder = BinaryPayloadDecoder.fromRegisters(result.registers, endian=Endian.Big)

watt = open("watt.txt", "w")

print >>watt, decoder.decode_32bit_float(),

#---------------------------------------------------------------------------# 

# close the client

#---------------------------------------------------------------------------# 

client.close()

On Monday, August 11, 2014 7:57:11 PM UTC+2, Bashwork wrote:

[Galen Collins]

Awesome, good work!

[nagarju...@connectm.com]

Awesome, good work!

i got error can you please solve this

error is:    builder = BinaryPayloadBuilder(endian=Endian.Big)

                 TypeError: __init__() got an unexpected keyword argument 'endian' 

[Galen Collins]

Looks like the arguments changed but not the documentation:

```

    def __init__(self, payload=None, byteorder=Endian.Little,

                 wordorder=Endian.Big):

```

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