Raspberry Pi-based SCADA prototype working
We are using a Rosemount model 3051S differential pressure transmitter to sense the pressure difference across a "baghouse" used to filter air vented from booths in a weld shop. The transmitter's 4-20 mA DC signal is sent through a 250 ohm resistor, producing a 1-5 volt DC voltage signal, which is sensed by the first analog input on a LabJack model T7 data acquisition unit. This data is then polled by a Raspberry Pi single-board computer running custom code (programmed in the "C" language, using the "libmodbus" library) and displayed in text form on the monitor.
This is very much a prototype system, put together hastily to demonstrate proof-of-concept. The final installation will be professional in quality.