Early data-acquisition (DAQ) systems were comprised of simple analog chart recorders. These were continuous strip chart recorders and circular recorders that plotted temperatures and setpoints of process parameters. The charts were cumbersome, hard to read with any resolution and required long-term storage/archiving of paper. The recorders also required a calibration schedule to ensure that accurate data was being plotted.
In the 1980s, personal computers became more affordable to the average user. The computer allowed for DAQ system software to communicate directly to process-control instruments and store this data digitally. Digital storage improves the analysis of data by presenting it in a functional, organized format. While most heat-treat shops utilize their systems for basic process storage such as temperatures, vacuum and carbon levels, the typical system consists of a computer residing in the corner of the met lab, only to be consulted when a customer calls with an issue or concern. However, an effective DAQ system helps prevent troublesome incidents before they arise and is more beneficial for handling those that do occur. This article will focus on data signals that are not typically logged or analyzed and practical uses for that data.