PyPCC

Python OPC-UA server to control the I2C devices in the LTS.

• pypcc2.py: OPC-UA server that expose (visible) variables and methods.

Prerequisites

Requirements

This Python3 code uses other Python3 modules:

• opcua
• recordclass
• yaml
• numpy

We recommend to install a virtual environment and then install the dependencies there. For convenience we have added the relevant modules to the file requirements.txt that can be used to install them with pip3: python3 -m pip install -r requirements.txt

Below are step-by-step instructions that show how to install the dependencies neatly in a Python3 virtual environment.

# Create a Python3 virtual environment with the name "env"
python3 -m venv env
# Activate the virtual environment
. env/bin/activate
# Update the already installed modules in the virtual environment since they are usually outdated
python3 -m pip install --upgrade pip wheel
# Deactivate the virtual environment and start it again
deactivate
. env/bin/activate
# And finally install the module dependencies
python3 -m pip install -r requirements.txt

Notes for using python3.11:

• install crypto 3.3 for asyncua
• add #define PY_SSIZE_T_CLEAN before #include <Python.h> in pyi2c.c in libi2c.

Install it

The software is installed by executing: python3 setup.py install

Execute it

The software can be executed using commandline parameters, for example specifying the config yaml file (RECVTR.yaml) and OPC-UA port (4840): hwtr -c RECVTR -p 4840

Alternativly the 4 hardware translators can be executed, using it's default parameters as:

• apscttr
• recvtr
• unb2tr
• apsputr

Install it as a service

The translators can also be installed as services:

• cp bin/*.service /lib/systemd/system/.
• systemctl daemon-reload
• systemctl enable recvtr.service so it is startup at boot
• systemctr start recvtr.service start the translator

The log can then be monited by journalctl -f -u recvtr.service

hwtr --help
usage: hwtr [-h] [-s] [-t] [-p PORT] [-l {DEBUG,INFO,WARNING,ERROR}] [-c CONFIG]

optional arguments:
  -h, --help            show this help message and exit
  -s, --simulator       Do not connect to I2c, but simulate behaviour.
  -t, --test            Do not start OPC-UA server.
  -p PORT, --port PORT  Port number to listen on [4842].
  -l {DEBUG,INFO,WARNING,ERROR}, --loglevel {DEBUG,INFO,WARNING,ERROR}
                        Log level [INFO].
  --loghost LOGHOST     Logstash host to which to forward logs []                    
  -c CONFIG, --config CONFIG
                        YAML config files, comma seperated [RCU]