The OM 402PID by Orbit Merret is a universal panel-mount PID regulator designed for flexible industrial process control. Its 24-bit sigma-delta ADC accepts DC voltage/current, process measurement (PM), RTD, thermocouple, and potentiometer inputs — covering virtually all standard industrial sensor types from a single instrument.

What input types does the OM 402PID accept?

Input ranges span ±60 mV to ±1200 mV DC, 0–20/4–20 mA, ±2 V to ±40 V, 0–100 Ω to 0–100 kΩ in 2/3/4-wire, Pt/Ni/Cu RTDs, and thermocouple types J, K, T, E, B, S, R, N, L. Linear potentiometer inputs (≥500 Ω) are supported with 2 VDC/6 mA excitation. An optional adjustable sensor excitation supply (5–24 VDC, 1.2W) can power external transmitters.

How does PID regulation work on the OM 402PID?

Control modes include parallel PID, PI, or proportional-only. Two regulatory relays (L3, L4) handle heating or cooling output — configurable as double two-state or PWM. An optional isolated analog output (16-bit DAC, 0–10V or 4–20 mA) serves heating, cooling, or both. Fourteen stored programs of up to 64 steps each support time-based (one-off or weekly), external-trigger, or front-panel start modes. Setpoints can be fixed, derived from an analog input, or selected from a program.

What output and communication options are available?

Two alarm relays (L1, L2, changeover) and two control relays (L3, L4, NO) are rated 250 VAC/3A. Optional SSR outputs (250 VAC/1A) replace relays for high-speed switching. Data interfaces include isolated RS232 or RS485 with ASCII, MESSBUS, Modbus RTU, or PROFIBUS DP protocols at baud rates from 600 to 230,400 Baud (up to 12 MBaud for PROFIBUS).

How does data logging work?

A built-in real-time clock records measured values at configurable intervals, storing up to approximately 265,000 data points in internal memory. Combined with the OM Link configuration software, this enables trend analysis, process auditing, and offline diagnostics without external data acquisition hardware.