# DigitalTwin1
## Digital twin for Beckhoff BK-9000 Modbus-TCP coupler (and compatible Wago device)


### Overview 

This tool connects to a Modbus-TCP coupler, reads it process image and publishes

* the new state of a discrete input register (digital input) after a change
* the new value of an input register (analog input) after a change
* periodically publishes the current values of all input registers (analog inputs)

using MQTT messages. The topic is built from a configured prefix and the index of the particular registers.

Furthermore it subscribes to MQTT messages related to the coils for the setup and anytime a message is received, it set the particular coils accordingly.


### Configuration

Configuration is done using a configuration file

    [modbus]
    client = 172.16.2.157
    scanrate = 0.25

    [mqtt]
    broker = 172.16.2.16
    digitalOutputTopicPrefix = dt1/coil
    digitalInputTopicPrefix = dt1/di
    analogInputEventTopicPrefix = dt1/ai/event
    analogInputPeriodicTopicPrefix = dt1/ai/periodic
    analogInputPublishPeriod = 10.0
    disableAnalogInputEventPublishing = true

### Operation details

While the input and discrete input registers are scanned with the configured scanrate, an action on a coil according to a received message is issued immediately. At the same time the all input registers are scanned.

Using a configuration option it is possible to disable the publishing of analog change event - if only periodic information (like for a thermometer or so) is required.

The MQTT messages related to change events of input or discrete input registers are marked as //retained//.


### Usage

The tool is simply started using

    python digitaltwin1.py

On default it searches the configuration file at ``$PWD/config``. This can be changed using the commandline argument ``-f``.

The Python modules ``pymodbus``, ``loguru`` and ``paho-mqtt`` are required.

A docker image with the required dependencies, the tool and a prepared default configuration in a volume is provided at ``registry.hottis.de/wolutator/digitaltwin1``.