Process Indicators & Control Units

Process Indicators & Control Units

Process indicators and control units provide local display, evaluation, and basic control of measured values at the point of need. They accept common signal types (current, voltage, RTDs, thermocouples) through universal inputs, convert those signals into readable engineering values, and present them on high-visibility displays suitable for varied ambient conditions. Beyond indication, many devices incorporate calculation, alarming, and relay logic to implement localized control functions.

This category spans loop-powered indicators, externally powered indicators with expanded I/O, and fieldbus-capable indicators. Loop-powered models operate directly in 4…20 mA circuits without an external supply and can be deployed in intrinsically safe applications. Fieldbus indicators support bus devices and display values communicated on the bus; PROFIBUS PA variants can act as “listeners,” while FOUNDATION Fieldbus devices can operate in listener mode or in standard function-block connections depending on the integration approach.

Indicators with control functions combine multiple capabilities in one enclosure - such as barrier/transmitter behavior with relay-based control actions - enabling limit monitoring, mathematical functions, differential-pressure calculations, and linearization without needing additional PLC programming for simple use cases. Portfolio options include panel-mount, field-mount, Ex-capable loop-powered units, multi-value HART display variants, and devices intended for straightforward fieldbus integration.

The main benefits are improved situational awareness and tighter local response. Clear local indication provides an extra layer of operational security when transmitter displays are inaccessible or unreadable. Commissioning and day-to-day operation are streamlined through device-level configuration and built-in functions, while broad approvals coverage (including Ex, marine, SIL, and other regional requirements) supports consistent deployment across diverse site areas.

Typical applications include local indication on tanks and pipelines, limit alarming for level/flow/pressure thresholds, small control loops using relay outputs, pump/valve interlocks, and fieldbus measurement value repetition at remote locations. Selection considerations include mounting environment, power strategy (loop vs external), required input types and accuracy, number/type of relay outputs, display readability and diagnostics, and how the device will be integrated into analog or fieldbus architectures.

Engineered Equipment Company, a leading supplier of specialized industrial equipment.