What machine are you trying to monitor? You will need an interface from the machine to the digital inputs.
Where do you want to view the data? A web page? Need more info to make accurate suggestion.
Anyway, I use a pro mini, ESP8266, text files and/or MySQL database, and php to save and display furnace data from my home. You write the software for your needs.
Data can include almost anything.
State of: Gas valve, Inducer motor, blower motor, call for heat, heat exchanger pressure drop (air flow)
Temperatures: incoming air, combustion exhaust, primary heat exchanger, etc.
Here is a live link showing my home furnace data.
Still have some things to do like AJAX for auto update and animations.