Europython 2006

Factory monitoring with Pylons, XML-RPC and SVG

3 Jul 2006, 12:10

30m

40-SS-D01 (CERN, Geneva)

Python in Science Python in Science

Speaker

Dr Rob Collins (Europython 2006 Conference)

Description

I write Python applications for a company specialising in industrial factory monitoring and scheduling. Most recently we have developed a web application for remote monitoring, sending text message alarms when machine hoppers run low. We're using the Pylons web framework, Myghty templating, XML-RPC and SimPy simulation. The dynamic graphical display of the factory is written in SVG, for Firefox (v1.5) web browser. We will look at interesting issues such as * the choice of framework and templating system, * the importance of decoupling threads using a log file and XML-RPC, * historical correction of data, * and why we needed simulation.

Summary

Summary

We provide a web-based factory monitoring system for the plastics industry. Machine
data is captured by an embedded web server in a box connected to up to four machines
in a factory. A Pylons web server polls the box for new data every 15 seconds. A
factory model is updated with the new data, which is displayed in dynamic, graphical
web pages on demand.

Interesting issues

• Choice of Pylons vs. other web frameworks.

• Choice of Myghty vs. other templating systems.

• Use of SVG objects for the factory mimic (graphical picture), showing the status of
  each machine, with dynamically created alarms.

• Decoupling input, analysis and display by the use of a time-adjusted log file.

• Use of XML-RPC for decoupling threads, so that one thread writes data for another,
  using the Pylons framework xmlrpc server.

• Use of XML-RPC to suck data out of standalone PCs running Visual Basic.

• Historical correction of data by entering missing log lines in the past, followed
  by reprocessing the log file to give a new current status.

• Use of wireless iPaq PDA for entering scrap and downtime reasons.

• Use of threading: stopping/starting/restarting.

• The need for simulation, and the simulation model.