Building our HMI
In the tradition of doing it all yourself, we decided to make our own PLC and design the HMI to control the brewhouse and the stills. Because owning the process is important to us, it was lost in translation.
This is written in Python using QT designer to make the interface. Mark has been designing the HMI whilst Eric codes.
What's a PLC? It stands for programmable logic controller, basically a PC that can convert commands and inputs into outputs that control devices in the distillery such as motors, drives and valves.
The HMI, the human machine interface is how we interact with the PLC in the real world. through the HMI we can control elements of the brew house and stills either automated or manually.
For the PLC we ditched the expensive world of locked in industrial automation and chose an open source language and an even more open source machine. The Raspberry Pi.
These amazing machines are solid state, fan less and perfect for running our software. Cheap and originally designed for schools and developing countries, they have a cult following as a single board computer that can control anything.
We used I-O Link as the digital connection protocol for our sensors and controllers. Essentially I-O link can connect our PC via a simple ethernet switch to our sensors, motors and valves in the distillery.
All the connections go to the I-O Link masters, shown above in orange. These hubs allow us to connect all our equipment to the Raspberry Pi via the green ethernet. We can also control the distillery via the internet, and its gives updates and alarms even when we are outside the building.
The HMI screens are tailored to our process and allow monitoring in real time of temperature, volumes, pumps and all aspects of the distillery.