The SA200L from RKC Instrument is an FM3545-approved compact temperature limit controller designed to serve as an independent safety layer in industrial heating processes. It occupies a 1/32 DIN footprint (48×24 mm) in a plug-in format — the internal assembly can be removed from the front panel without disturbing wiring.

How does the latching safety output work?

When the process temperature exceeds the preset limit, the relay output activates and remains latched — even after the temperature returns to normal. The output can only be reset by a deliberate human action: pressing the front key, triggering a digital input, or sending an RS-485 command. This ensures the fault condition is acknowledged before the process can restart.

How does it differ from a standard temperature controller?

A standard controller modulates temperature to a setpoint. The SA200L does not control — it monitors independently and cuts power if a limit is breached. It is deployed alongside a primary controller as a safety device, not a replacement for one. The FM3545 certification means it has been tested and listed as a Temperature Limit Switch for fire prevention applications.

What input types are supported?

Thermocouples (K, J, T, S, R, E, B, N, W5Re/W26Re, PLII, U, L), RTD (Pt100, JPt100), DC voltage (0–5 V, 1–5 V, 0–10 V), and DC current (0–20 mA, 4–20 mA with 250 Ω external resistor). Measurement accuracy: ±0.3% of displayed value + 1 digit.

What communication options are available?

Optional RS-485 with Modbus or ANSI protocol, supporting up to 31 units on a single bus. The SA200L also includes an overtemperature timer that measures the duration of over/under-temperature events and retains peak value data, plus a password lock to protect safety-critical parameters from unauthorized changes.