Measurements of process parameters have historically been accomplished by the analog panel meter (APM). Since 1819, when Oersted proved the existence of current in a wire by using a compass needle positioned next to a conductor, APMs have been the main indicator for all kinds of monitoring. (more...)
![Digital Bargraph Meter](https://www.weschler.com/wp-content/uploads/2020/01/BG241-yel500.jpg)