The ENDA ET7420 is a self‑tuning PID digital temperature regulator for industrial heating and cooling control, built into a 72 × 72 mm panel‑mount housing with an IP65‑rated front panel. It combines a dual 4‑digit LED display with a universal input stage that accepts Pt100 RTD and six thermocouple types (J, K, L, T, S, R) from a single device. The Self‑Tune algorithm automatically calculates optimal PID parameters by measuring the thermal response of the connected load during a single heating cycle, eliminating manual PID tuning in the field. The selectable relay or SSR control output plus two configurable alarm relays (AL1 and C/A2) provide the output flexibility to drive contactors, solid‑state relays, solenoid valves, and external alarm indicators.

Self‑Tune PID Control & Soft‑Start

• Self‑Tune — Automatic Parameter Calculation: The Self‑Tune function measures the thermal response of the connected system during a single heating cycle and automatically calculates the optimal PID constants. It can be activated at any time—not only at startup—which is particularly useful for batch processes where the thermal load changes with each fill level. The algorithm supports PID, PI, PD, P, and ON/OFF control modes, all selectable from the front‑panel menu without external software.
• Soft‑Start Ramp Function: When enabled, the soft‑start function gradually ramps the output power from zero to the required level over a configurable period. This protects the heating elements from thermal shock during cold starts and prevents inrush current spikes that could trip upstream circuit breakers.

Seven Sensor Inputs — One Controller for All Your Probes

• Pt100 RTD and Six Thermocouples: The sensor type is selectable from the front panel menu, covering Pt100 (-200 to +600 °C), J (0–600 °C), K (0–1200 °C), L (0–600 °C), T (0–400 °C), S (0–1600 °C), and R (0–1600 °C). A single ET7420 can replace multiple controller variants in your spares inventory, reducing purchasing and storage complexity across multi‑process facilities.
• Input Offset for Sensor Positioning: A programmable input offset compensates for known thermal gradients between the probe location and the actual measurement point, ensuring the displayed temperature reflects the true process value, not just the sensor tip reading.

Flexible Output Architecture & Communication

• Selectable Relay or SSR Output: The main control output can be configured as a mechanical relay (2 A/250 V AC, NO, for resistive load) or a logic‑level SSR drive (max 24 V, 20 mA). The relay output has a life expectancy of 300,000 electrical operations and 30,000,000 mechanical operations, making it suitable for years of continuous cycling in production environments.
• Dual Alarm Relays: The AL1 relay (NO/NC configurable, 4 alarm output types) is dedicated to the first alarm output. The C/A2 relay can be independently programmed as a second alarm output or as the cooling control output in heat/cool PID mode. This dual‑relay architecture enables a single ET7420 to provide control, alarm annunciation, and cooling actuation simultaneously.
• Heating & Cooling Control: The controller can be configured for heating‑only, cooling‑only, or combined heating/cooling PID control. In combined mode, the C/A2 relay serves as the cooling actuator output while the main control output drives the heating element—one ET7420 managing both sides of a thermal process.
• Optional RS‑485 Modbus RTU: The optional galvanically‑isolated RS‑485 interface supports the standard Modbus RTU protocol for integration with PLCs, SCADA, and PC‑based management systems. All process variables, setpoints, and alarm states are accessible via Modbus registers, and the controller can be programmed remotely through Modbus.

Designed for Reliable Industrial Operation

• Sensor Failure Protection: In the event of a probe defect—open circuit, short circuit, or out‑of‑range reading—the controller can be configured to run the output periodically at a user‑defined duty cycle or hold the output in a fixed relay state, maintaining basic process continuity during sensor maintenance.
• 3‑Level Parameter Access Protection: Parameter access is protected on three levels—Operator, Supervisor, and Administrator—preventing accidental or unauthorised changes to validated control settings in regulated environments.
• Wide‑Range Power Supply Options: Standard 230 V AC +10%/−20% supply. Optional 24 V AC ±10% or 9‑30 V DC / 7‑24 V AC SMPS for low‑voltage control panels, enabling a single model to be deployed across different machine electrical architectures.
• IP65 Front Panel Protection: The sealed front panel withstands dust ingress and low‑pressure water jets, suitable for installation in industrial control cabinets exposed to washdown or particulate environments.

Applications

• Plastics extrusion and injection molding barrel temperature control
• Packaging machinery: heat sealing, blister pack forming, shrink‑wrap tunnels
• Industrial ovens and furnaces for heat treatment
• Motorized valve control for heating and cooling circuits (with C/A2 output configured for cooling)
• General industrial heating/cooling processes requiring compact 72×72 mm PID control, universal input, and Modbus integration