Monitoring system for wasted water plant

Architecture

The plant is operated by a Schneider Twido PLC, that have a MODBUS TCP/IP interface to read and set parameters.

The original design of SCADA is based on QT. But to make use of new browser technologies like event-stream, flask and many others, is now completly redesigned.

Main interface is Twitter Bootstrap based flask aplication. Data adquisition is made with a custom thread based python daemon.

Modbus comunication is provided by twisted based pymodbus library. All adquired data is stored in a MySQL Database, the selected ORM is peewee, that is lightweight and simple.

Main Data entities

• event_log
• alarm_log
• level_log
• oxigen_log
• cloudiness_log

Data Adquisition Strategy

To aquire data from PLC, we made a MODBUS/TCP client conection, and poll for data ever half second. In this step all data is pushed in json format througth a event-stream connection to brower, updating graphs and aplication info.

How to test application

Yo need to have following packages installed:

• Python 2.6 or 2.7 (preferred)
• Redis: http://redis.io
• Python distribute #FIXME ¿Is virtualenv there??

How to get this thing working

• Create a new virtualenv for application: virtualenv env
• Install requirements: pip install -r requirements.txt
• Start redis (if you not started it yet)
• Configure redis connection on arakur_ww/config.py
• Start PLC mock: python mock_planta/server.py
• Start adquisition daemon python arakur_ww/daemon.py
• Start Web server python arakur_ww/arakur_ww.py
• Enter to http://localhost:5000 using a modern browser

Production deploy

Target linux is Ubuntu 12.10

• Install dependencies
• Create a new user "hmi"
• Clone repository inside home directory of this user
• Add execution rights to web.py and adquisitor.py (chmod +x)
• Copy upstart jobs from upstart_jobs to /etc/init
• Start jobs, manually: start sbr_daemon, start sbr_web

FAQ

Where is the PLC program?

Sorry, I only develop the HMI, but, if you write to the apropiate Modbus registers, (defined in arakur_ww/constants.py), everything have to work well

Why you have twisted, and serve the application with Flask?

Is a design choice, Because flask is really confortable to work with, and really, web app and adquisition daemon are different services.

Why this FAQ?

Because... you are reading It.