Valmet A413110 TIU6 Board – Revision M1 (Temperature Input Unit)

The Valmet A413110 TIU6 (Temperature Input Unit) is a dedicated 6‑channel temperature measurement board for the Valmet DNA distributed control system. The revision M1 introduces improved cold‑junction compensation accuracy, enhanced EMC filtering, and a faster analog‑to‑digital converter compared to earlier revisions. This module is designed to interface directly with thermocouples, RTDs, and millivolt sources, providing high‑resolution temperature data for critical process loops.

Input Channel Configuration

The TIU6 provides six differential input channels, each individually configurable for: thermocouple types (J, K, T, E, N, R, S, B), RTDs (Pt100, Pt1000, Ni100 in 2‑, 3‑, or 4‑wire connection), or raw millivolt signals (0‑100 mV). Each channel includes a dedicated precision current source for RTD excitation and an input impedance of >10 MΩ for thermocouple and mV modes. The terminal block is equipped with an integrated cold‑junction compensation (CJC) sensor that maintains reference junction accuracy to within ±0.2 °C.

Measurement Accuracy and Resolution

The module utilizes a 24‑bit Sigma‑Delta ADC with an effective resolution of 19 bits for thermocouples and 21 bits for RTDs. Basic accuracy is ±0.05 % of reading ±0.4 °C for thermocouples (excluding sensor error) and ±0.02 % ±0.1 °C for RTDs. The sampling rate per channel is programmable from 2 Hz to 50 Hz, with built‑in digital low‑pass filtering to suppress 50/60 Hz power‑line noise. The M1 revision adds an offset cancellation algorithm that reduces residual drift over the entire operating temperature range.

Galvanic Isolation and Protection

All six input channels are galvanically isolated from the system logic and from each other with a 1500 V AC test voltage. This isolation breaks ground loops and protects against common‑mode voltages up to 250 V. Each input includes transient suppression diodes and reverse‑voltage protection. The RTD excitation current is limited to 1 mA to prevent self‑heating of the sensor. The module also features a built‑in open‑circuit detection mechanism that flags broken sensors in the status register.

Communication and Data Interface

The TIU6 communicates with the host controller over the Valmet backplane bus using a high‑speed serial link. It transmits fully linearized temperature values in engineering units (°C or °F), as well as raw ADC counts for diagnostic purposes. The module supports cyclic data transfer with a typical update rate of 100 ms for all six channels. A diagnostic data block is also available, containing internal temperature, supply voltage, and channel health bits (open circuit, short circuit, out‑of‑range).

Hardware Design and Mounting

The A413110 is a 6U x 4HP Eurocard (233 mm x 20 mm) that fits into any standard Valmet subrack. The front panel features a green LED for module power and six amber LEDs that indicate channel activity and fault status. The field wiring is terminated via a 20‑pin screw‑type terminal block (removable) that accepts wires up to 1.5 mm². The board draws 300 mA from the 5 V rail and 40 mA from the 24 V rail. A front‑mounted push‑button initiates a manual self‑test sequence.

Environmental and Reliability Ratings

Operating temperature range: 0 °C to +55 °C; storage: ‑40 °C to +85 °C; humidity: 10‑95 % non‑condensing. The module is conformal coated to protect against dust and moisture. It complies with EN 61010‑1 safety standards and EN 61326‑1 EMC requirements. MTBF is estimated at 850,000 hours at 40 °C.

Installation and Commissioning

Insert the TIU6 board into a free rack slot, ensuring full seating in the backplane connector. Connect the sensor cables using twisted‑pair shielded wiring – the shield should be grounded at the module side only. Use the Valmet Engineering Tool to configure each channel’s sensor type, temperature unit, and filter time constant. Perform a calibration check using a precision thermocouple simulator or RTD simulator; the module supports software offset and gain adjustments.

Typical Applications

The TIU6 is widely used in paper machine dryer sections (surface temperature monitoring), chemical reactor temperature profiling, steam header temperature measurement, and bearing temperature monitoring on rotating equipment. Its six‑channel format is ideal for small to medium temperature point density.

Maintenance and Firmware

Periodic inspection of the terminal connections and cleaning of the PCB is recommended. Firmware updates are performed over the backplane using the system loader. The M1 revision includes a lifetime counter that can be queried to monitor operating hours. If a channel fails, the diagnostic LEDs will indicate the specific fault. The module can be replaced without shutting down the entire rack.

Conclusion

The Valmet A413110 TIU6 Board Ver.M1 provides precise, stable, and reliable temperature acquisition for critical control applications. Its high accuracy, comprehensive diagnostics, and robust isolation make it an indispensable component in the Valmet DNA temperature monitoring framework.