Correct parameters for reading input registers.

[s s]

Hi,
I have a Raspberry Pi connected to an SDM630 smart meter and I'm trying to setup a serial modbus communication.
However, I'm not an expert in the modbus protocol and I'm not entirely sure what parameters should I use.
This is the modbus documentation for the device http://www.ausboard.net.au/index_files/Eastron/Eastron%20Modbus%20Registers.pdf
In the table "Input Registers" I can see the following:

---------------------------+-----------------------------+-------------------------------------------------+-------------------------------------------------
Address  (Register)    |   Parameter Number    |   SDM630 Input Register Parameter       |    Modbus Protocol Start Address Hex 
---------------------------+-----------------------------+-------------------------------------------------+-----------------------+------------------------

                                   |                                      |   Description                           |   Units   |     Hi Byte               |            Lo Byte
---------------------------+------------------------------+-------------------------------------+----------+-----------------------+------------------------
30001                        |                1                      | Phase 1 line to neutral volts. |    Volts   |       00                    |          00
---------------------------+------------------------------+-------------------------------------+----------+-----------------------+------------------------
30003                         |               2                      | Phase 2 line to neutral volts. |    Volts   |       00                    |           02
---------------------------+------------------------------+-------------------------------------+----------+-----------------------+------------------------
30005                        |                3                      | Phase 2 line to neutral volts. |    Volts   |       00                    |           04
---------------------------+------------------------------+-------------------------------------+----------+-----------------------+------------------------
...
...
...

And here is my code:

#!/usr/bin/env python

from pymodbus.client.sync import ModbusSerialClient as ModbusClient
import logging

logging.basicConfig()
log = logging.getLogger()
log.setLevel(logging.DEBUG)

client = ModbusClient(method='rtu', port='/dev/ttyAMA0', timeout=10)
client.connect()

rr = client.read_input_registers(30001, 2)
print rr

client.close()

And this is the output:
DEBUG:pymodbus.transaction:Running transaction 1
# 10 seconds delay which matches my timeout
DEBUG:pymodbus.transaction:getting transaction 1
None

So my question is what parameters should I supply to the read_input_registers() if I want to read the electric potential on phase 1? I know the value is contained in two registers.
Also what is "Modbus Protocol Start Address Hex" and how is it different than "Address  (Register)"?

Thank you.

[Jurek Kędra]

Hello,

I guess you need slave address to be supplied (unit=).

Try to use read_holding_registers instead as in an example below:

rr = client.read_holding_registers(0, count=8, unit=0x01)

Good luck,

Jurek

[Jeroen van Wouwen]

Hi,

I have the same config and I wonder if you have the script running or finished?

When i run your data that I change a bit, I get output but I have no idea what to do with the data.

Can you help me with the script so I can use it to monitor the kwh meter.

I spend more than 20 hours on the config but still no luck.

I hope you can sent me in the right direction.

# python ./test.py

DEBUG:pymodbus.transaction:Running transaction 1

DEBUG:pymodbus.factory:Factory Response[4]

[31179, 17254, 24898, 17254, 48006, 0, 0, 0, 0, 0, 0, 16562, 2525, 16550, 6507, 16539, 47336, 16572, 64062, 16560, 29765, 16551, 15818, 0, 0, 0, 0, 0, 0, 16256, 0, 16256, 0, 16238, 24029, 16796, 48708, 16797, 52424, 16811, 8670, 17254, 34695, 0, 0, 0, 0, 0, 0, 0, 0, 16761, 60952, 0, 0, 16773, 10163, 0, 0, 49335, 59877, 16256, 0, 0, 0, 16801, 39708, 0, 0, 16968, 14017, 16138, 15729, 0, 0, 15639, 36176, 15878, 9437, 15855, 40370, 16138, 40824, 16766, 3044, 16768, 65146, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 16774]

#!/usr/bin/env python

from pymodbus.client.sync import ModbusSerialClient as 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(1,100, unit=0x01)#For debugging

print rr.registers

client.close()

Op maandag 27 januari 2014 09:30:56 UTC+1 schreef s s:

[MemyselfandI]

Hello @all,

did you solve the poblem?

[Oytun Oktay]

The resulting array composed of 16bit data which should be used to get their corresponding 32bit float representation.https://en.wikipedia.org/wiki/Floating_point

[Tushar Borhade]

I am getting this at output!

Need help

True

DEBUG:pymodbus.transaction:Running transaction 1

DEBUG:pymodbus.client.sync:will sleep to wait for 3.5 char

DEBUG:pymodbus.transaction:recv: 0x1 0x4 0x10 0x3 0xef 0xfe 0xff 0xcf 0x40 0x10 0x2 0x7c 0xbf 0xff 0x80 0xe8 0xff

DEBUG:pymodbus.factory:Factory Response[1]

DEBUG:pymodbus.transaction:adding transaction 0

DEBUG:pymodbus.transaction:getting transaction 1

Traceback (most recent call last):

  File "test8.py", line 26, in <module>

    print result.registers 

AttributeError: 'ReadCoilsResponse' object has no attribute 'registers'