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Implementation of the RCT Power communication protocol

Project description

rctclient - Python implementation of the RCT Power GmbH "Serial Communication Protocol"

This Python module implements the "Serial Communication Protocol" by RCT Power GmbH, used in their line of solar inverters. Appart from the API, it also includes a registry of object IDs and a command line tool. For development, a simple simulator is included.

This project is not in any way affiliated with or supported by RCT Power GmbH.


Below is a quickstart guide, the project documentation is on Read the Docs.


Install and update using pip:

$ pip install -U rctclient

To install the dependencies required for the CLI tool:

$ pip install -U rctclient[cli]


Let's read the current battery state of charge:

import socket, select, sys
from rctclient.frame import ReceiveFrame, make_frame
from rctclient.registry import REGISTRY as R
from rctclient.types import Command
from rctclient.utils import decode_value

# open the socket and connect to the remote device:
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect(('', 8899))

# query information about an object ID (here: battery.soc):
object_info = R.get_by_name('battery.soc')

# construct a frame that will send a read command for the object ID we want, and send it
send_frame = make_frame(command=Command.READ, id=object_info.object_id)

# loop until we got the entire response frame
frame = ReceiveFrame()
while True:
    ready_read, _, _ =[sock], [], [], 2.0)
    if sock in ready_read:
        # receive content of the input buffer
        buf = sock.recv(256)
        # if there is content, let the frame consume it
        if len(buf) > 0:
            # if the frame is complete, we're done
            if frame.complete():
            # the socket was closed by the device, exit

# decode the frames payload
value = decode_value(object_info.response_data_type,

# and print the result:
print(f'Response value: {value}')

Reading values from the command line

The module installs the rctclient command (requires click). The subcommand read-values reads a single value from the device and returns its output. Here is a call example using the object ID with verbose output:

$ rctclient read-value --verbose --host --id 0x959930BF
#413 0x959930BF battery.soc         SOC (State of charge)              0.29985150694847107

Without --verbose, the only thing that's printed is the received value. This is demonstrated below, where the --name parameter is used instead of the --id:

$ rctclient read-value --host --name battery.soc

This makes it suitable for use with scripting environments where one just needs some values. If --debug is added before the subcommands name, the log level is set to DEBUG and all log messages are sent to stderr, which allows for scripts to continue processing the value on stdout, while allowing for observations of the inner workings of the code.

Generating the documentation

The documentation is generated using Sphinx, and requires that the software be installed to the local environment (e.g. via virtualenv). With a local clone of the repository, do the following (activate your virtualenv before if so desired):

$ pip install -e .[docs,cli]
$ cd docs
$ make clean html

The documentation is put into the docs/_build/html directory, simply point your browser to the index.html file.

The documentation is also auto-generated after every commit and can be found at

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