This project was realized in 2015 for the end of my college studies and as part of the CRÉE TA VILLE (CREATE YOUR CITY) contest, which challenged the participants to carry out innovative projects aimed at improving the city of today and creating the city of tomorrow.
My proposed project, the Connected Factory, allows the user to monitor each of his connected devices simultaneously and download the reading history (logged data) in csv format for each device. From the web page, the devices can also be configured (e.g., delete the data history, change device name, change device range, change device output type). In industrial process control, analog 4–20 mA current loops are commonly used for electronic signalling, with the two values of 4 & 20 mA representing 0–100% of the range of measurement or control. Based on this de facto standard, the modules can be used on any existing equipment that follows this standard, or that outputs a direct current voltage.
The data capture module reads the input data every five seconds and transmits if wirelessly to the data processing module.
This module is composed of a power supply circuit, a conversion circuit
(for 4-20 mA input readings), a protection circuit and a microcontroller
(PIC18F4620) connected to a Digi XBee RF module with a
regulator. With the help of its internal ADC, the
microcontroller reads the input voltage every five seconds using a timer
interrupt and communicates the digital value to the XBee module with his
built-in UART module, adding the device ID to the message transmitted
(format: <ID-Data>). The XBee module relays the message wirelessly to
the data processing module.
For every equipment the user wants to monitor, simply add a data capture module and connect it to the equipment's output. Once connected and powered, the module will start transmitting the data immediately to the master XBee module (data processing module), and the new equipment will automatically appear on the monitoring web page.
On the data processing side, the master XBee module continuously receives the data from the data capture modules and transmits it to the microcontroller (Arduino Uno). The Arduino Uno was used with an Ethernet shield to communicate the data to the server, which helped rapidly prototype this project for the timeframe imposed.
Whenever the microcontroller receives a packet on its serial port, the
packet is read and its content is stored in a buffer until the packet is
received completely. With the help of the delimiters (<, -, >),
the device ID and data are parsed and transmitted to the server via
Ethernet with the help of GET requests.
Although the server can be run on pretty much any compatible machine with MySQL, a BeagleBone Black was used and configured to run the server-side scripts. The embedded computer was running under the Debian Linux distribution, and automatically assigned itself a static IP on your private network when powered on.
On the front-end, the web page is developped in HTML5 with Bootstrap for a responsive monitoring system. Different PHP5 scripts are executed on the back-end side whenever the user accesses the web page, tries to modify a device's configuration, or downloads/deletes the logged data history.
On the main page, the different devices connected are displayed along with their current readings, which are updated every 5 seconds. Each device connected is automatically displayed when accessing the page, so a simple page refresh suffices for a newly connected device to appear. Because all of the reading data is automatically stored in the server's MySQL database, the data history for each device can easily be downloaded in csv format.
Disclaimer: prior to this project (2015), I had no web programming experience (and basically had just started programming in C). Throughout this project, I improved my programming abilities and learned HTML, PHP & SQL.