Many European process plants still run on 4-20mA temperature loops installed decades ago, and while that infrastructure keeps doing its job, a bare current loop can’t deliver the sensor drift, wiring fault, and calibration data that predictive maintenance and digitalisation programs depend on. This article explores why full replacement with fieldbus or wireless is rarely practical, given the capital outlay, shutdown time, and safety loop revalidation involved. It explains how HART, already supported by most transmitters installed in the last 20 years, carries additional process variables and diagnostics over the same field wiring, and how HART multiplexers and interface modules can pull that data without interrupting the process. It also looks at where this approach falls short, including slow data rates, older devices with limited HART support, and the organizational challenge of putting the data to work. Readers will come away with a practical, loop-by-loop path to close the visibility gap and find out how much capability their plant already has sitting idle. Read the full article from October 2026 issue of Control Engineering Europe.
Rugged instrumentation for reliable measurement and control
Extended Applications Semiconductor & Microelectronics
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