On our own build machine, we use Fanuc PLC to control them but as AI_The_Man said, our older manual setup was to act directly on relays that control everything(valve solenoid starter...). For our new machine, we all passed through the PLC so we can add safety feature in manual process.
I never tryed them yet but Automation direct have some cheap PLC that seems to be popular.
The first thing I would advice you is to find the electrical schema of that machine. If you can have a hand on it, it would save you times. If you cannot have it, take away all wirings and stuff! Most of times it's more quick to rewire everything compare to try to find which wire do what.
If you have money to build something great, I would say go for HMI to control all your machine, like controlling temperature, controling valve solenoid... everything! After that, if you need to know a specific value (times, counts, how many cycle, switch glitching problem...) or add special process feature (safety, close-loop motion...) you will only have to program it. Also, you would have everything you need to setup at one only place, the screen!  |