Process Indicators & Control Units

Process Indicators & Control Units

Process indicators and control units provide local visibility and evaluation of measurement signals at the point where decisions are made. They range from simple loop-powered displays to multi-function indicators that calculate, alarm, and switch outputs. By adding a clear, readable display and configurable logic, they turn raw signals into actionable information close to the process.

These devices commonly accept universal analog inputs, enabling connection of current and voltage signals as well as RTDs and thermocouples. Loop‑powered indicators operate directly in 4–20 mA measuring circuits without requiring a separate supply and can be applied in intrinsically safe installations. For additional transparency on smart loops, indicators can remain HART‑transparent while displaying multiple values from a single device where supported.

For digital architectures, fieldbus indicators read values communicated on the bus and display them locally. This supports FOUNDATION Fieldbus and PROFIBUS PA environments where local indication is required without changing the underlying control strategy. Depending on implementation, operation can be configured as a listener-style device or as an active participant using standard function block connections.

Control-capable variants extend beyond indication. Functions such as limit value monitoring, mathematics, differential pressure calculations, and linearization allow a single unit to handle common “small logic” tasks. Some designs integrate multiple roles - such as barrier, transmitter power, and relay-based control - so indication, conditioning, and switching are combined in one compact device, simplifying cabinet layouts and field junction boxes. Benefits also include faster, more comfortable commissioning and operation, additional security through local readout, and options with international approvals (e.g., Ex and SIL) for use in demanding environments. Integration support for bus systems helps keep local indication aligned with digital architectures.

Typical applications include panel-mounted indication on packaged skids, field-mounted indicators at remote assets, and loop-powered displays in hazardous areas where adding a power supply is undesirable. Fieldbus indicators are used on segments where local readback is needed for commissioning and troubleshooting, while control units cover standalone functions such as limit alarming, local interlocking, or simple pump/valve control alongside analog measurement.

Forberg Smith, an exclusive authorized representative of sales and service for Endress+Hauser.