What are electronic recorders that can record more than one process variable called?

Multi-pen recorders are specifically designed to monitor and record more than one process variable simultaneously. This capability allows them to track different measurements, such as temperature, pressure, and flow rates, on a single graph, providing a comprehensive view of various data points over time. Each pen on the recorder represents a different variable, allowing operators and engineers to analyze relationships and correlations between these variables in their processes. This versatility is crucial in complex instrumentation setups where multiple parameters need to be monitored for optimal control and performance.

While single-pen recorders are limited to tracking only one variable at a time and other types of recorders like analog and standard recorders may have specific functions, they do not possess the multi-variable recording capability that multi-pen recorders offer. This makes the designation of "multi-pen" distinctly fitting for devices capable of handheld recording across multiple variables.