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My solar panels are connected to an Omnik Inverter (5000tl2). That company has gone bankrupt and the available documentation does not specify the use of the USB port or the registers on the inverter itself.

I am trying to read data thats on the inverter without the use of the wifi module. I connected my Pi 2B+ to the USB port, installed pymodbus and tried this code (courtesy of Fasthook) which is originally meant for another brand (GROWATT):

import subprocess
from time import strftime
import time

from pymodbus.client.sync import ModbusSerialClient as ModbusClient

client = ModbusClient(method='rtu', port='/dev/ttyUSB0', baudrate=9600, stopbits=1, parity='N', bytesize=8, timeout=1)
client.connect()
rr = client.read_input_registers(1,44)

rr = client.read_input_registers(2,1) #Watts delivered by panels (DC side)
value=rr.registers
pv_watts=float(value[0])/10
rr = client.read_input_registers(3,1) # Volts on DC side
value=rr.registers
pv_volts=float(value[0])/10
rr = client.read_input_registers(4,1) # Amps on DC side??? Not sure.
value=rr.registers
pv_amps=float(value[0])/10
rr = client.read_input_registers(12,1) #watts delivered by inverter to net
value=rr.registers
out_watts=float(value[0])/10
rr = client.read_input_registers(13,1) # frequency of AC
value=rr.registers
ac_hz=float(value[0])/100
rr = client.read_input_registers(14,1) # volts on AC side delivered by inverter
value=rr.registers
ac_volts=float(value[0])/10
rr = client.read_input_registers(27,1) # Total energy production today
value=rr.registers
Wh_today=float(value[0])*100
rr = client.read_input_registers(29,1) # Total energy production in inervter storage
value=rr.registers
Wh_total=float(value[0])*100
rr = client.read_input_registers(32,1) # Inverter temperature
value=rr.registers
current_temp=float(value[0])/10

client.close()

I also started PyModBus Debugging that gives me:

  • DEBUG:pymodbus.transaction:Current transaction state - IDLE
  • DEBUG:pymodbus.transaction:Running transaction 1
  • DEBUG:pymodbus.transaction:SEND: 0x0 0x4 0x0 0x1 0x0 0x2c 0xa1 0xc6
  • DEBUG:pymodbus.client.sync:New Transaction state SENDING
  • DEBUG:pymodbus.transaction:Changing transaction state from SENDING to WAITING FOR REPLY
  • DEBUG:pymodbus.transaction:Transaction failed. (Modbus Error: [Invalid Message] Incomplete message received, expected at least 2 bytes (0 received))
  • DEBUG:pymodbus.framer.rtu_framer:Frame - [b] not ready
  • DEBUG:pymodbus.transaction:Getting transaction 0
  • DEBUG:pymodbus.transaction:Changing transaction state from PROCESSING REPLY to TRANSACTION_COMPLETE

This error is from: rr = client.read_input_registers(1,44)

My guess is that the registers from a GROWATT are different from the Omnik. That is not surprising :) As i can't find any documentation on the Omnik itself... how can i determine the right code for my Omnik Inverter?

Many thanks for any help on this!

Bart

Scoobie
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1 Answers1

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Interested to in finding this out

My 2 cents but not enough done yet with this stuff

https://ginlongsolis.freshdesk.com/support/solutions/articles/36000340158-modbus-communication-for-solis-inverters

A mapping for V4 protocol https://github.com/XtheOne/Inverter-Data-Logger/blob/master/InverterMsg.py

These settings could be different (19200 baud for omnik?) ----Baud rate：9600bps ----Parity checking：None ---- Data：8 ---- Stop：1

So SEND: 0x0 0x4 0x0 0x1 0x0 0x2c 0xa1 0xc6

0x0 is the slave (shouldn't this then be 0x01) 0x4 is the function to read detail information from the inverter 0x0 0x1 is then adress 1 (or 2 if we start on 0) 0x0 0x2c is then 44 bytes to be returned 0xA1 0xC6 would then be the CRC check (how to calculate)

junkew
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