Process Indicators & Control Units

Process Indicators & Control Units

Process indicators and control units provide a local decision point in the measurement chain: they display values where they are needed, evaluate them against defined criteria, and - when required - initiate simple control actions. Analog measured values can be indicated, evaluated, and calculated, with large displays designed for readability under varied ambient conditions. Positioned close to the loop, they keep the measured value visible and usable even when higher-level systems are unavailable.

Flexibility comes from universal input capability. The same platform can accept current, voltage, RTD, and thermocouple signals, reducing spare-part variety and simplifying panel standards. Loop‑powered indicators require no separate power supply and can be inserted directly into 4–20 mA circuits, which also supports intrinsically safe installations. Fieldbus indicators extend the concept by indicating values communicated on the bus.

Control units expand beyond display into monitoring and actuation. Typical functions include limit value monitoring, basic mathematics, differential pressure functions, linearization, and other calculations that allow local decisions to be made with minimal engineering overhead. Where appropriate, devices can combine multiple roles - such as barrier, transmitter, and relay-based control - providing compact control points with clear field-side feedback.

Benefits include fast, straightforward commissioning and troubleshooting through immediate local feedback, plus additional security through on‑site measured value display. Depending on model, international approvals (e.g., Ex, marine, SIL, WHG) support deployment in regulated environments and safety-related applications. Integration into bus systems and the ability to display multiple values (including HART display variants) reduce engineering effort when standardizing across mixed assets.

Typical applications include local indication at tanks, filters, and remote packages; redundant display for critical loops; alarm annunciation and simple interlocks via relay outputs; and compact control for dosing, pumping, or level/flow-related functions. In fieldbus systems they provide a convenient local window into bus values without reengineering the control layer, improving maintainability and situational awareness in the field.

Field Instruments & Controls, Inc. an exclusive authorized representative of sales and service for Endress+Hauser.