Task was to retrofit autoclave machine based on Siemens S5 system, together with complete electrical cabinet and its protection and switching elements.
Machine had fairly low number of elements, with final S7 configuration consisting of 60 signals.
Why did I say final S7 config? As there were significant differences in old S5 and new S7 hardware configuration.
In short, machine consists of 11 on/off valves and unregulated water pump, fan and auxiliary conveyor.
Automation task is to control temperature and pressure inside machine following Recipe curve for both temperature and pressure. Both are regulated through on/off valves, feeding in hot steam or cold air and venting-out valves.
Automation task for this project was also to include separate PC with SCADA software for Recipe creation and batch logging, tasks that were originally based on local controllers and matrix printer, all independent from S5 CPU.
S5 CPU was only responsible for cooling fan and auxiliary conveyor used on the beginning and the end of technological process.
There were no much help from existing S5 software, as most of automation functions will have to be implemented from scratch, and combining old partial solutions to new automation seemed like useless work.
Another lucky coincidence was that machines were still mostly in working condition, and investor had personnel that were highly familiar with technological process.
All of this made selection of migration tactics straight forward: observe machine while running, trying to note all the functions machine performs.
