The RT28U is a programmable digital controller by Comeco Control & Measurement that accepts virtually any industrial temperature or process sensor through a single universal input. Whether the application uses a Pt100 RTD, a K-type thermocouple, or a 4–20 mA transmitter, the RT28U scales and displays the reading on a bright 3-digit LED and switches up to two relay or SSR outputs at the programmed set point.

What sensor types can the RT28U accept?

The universal input handles Pt100 (–100 to +850 °C), Pt1000 (–100 to +600 °C), PTC thermistors (–50 to +150 °C), and thermocouples J, K, T, S, R, and B — covering –40 to +1000 °C depending on the sensor. Linear inputs accept 0–10V, 0/4–20 mA, and 0–1 kΩ with fully programmable scaling from –199 to +999. An optional 24V DC loop supply powers 2-wire transmitters directly from the controller. Cold junction compensation and RTD lead resistance compensation are automatic.

What output configurations are available?

The RT28U supports up to two independently configurable outputs: electromechanical relays (5A/250VAC, NO/NC or NO), solid-state relay drive (1A/250VAC), or MOS gate (0.1A/60V, optically isolated). An external SSR driver output (5–24V DC, 30 mA) is also available. Combined with five DIN panel formats — 96×96, 96×48, 48×96, 48×48, and 72×36 mm — and optional IP65 front protection and RS485 serial communication, the RT28U scales from simple thermostat replacement to networked multi-controller installations.