Foxboro FBM37 RTD Input Interface Module

The Foxboro FBM37 is a high‑performance, 8‑channel RTD input module designed for the Foxboro I/A Series™ and EcoStruxure Foxboro (Foxboro Evo™) DCS platforms, originally developed by Invensys and now part of Schneider Electric’s industrial automation portfolio. Built for precision temperature measurement using platinum and nickel RTD sensors, it delivers accurate, stable, and noise‑immune data for critical process control. With full channel‑to‑channel isolation, hot‑swap capability, comprehensive diagnostics, and a rugged compact form factor, the FBM37 is ideal for chemical, oil and gas, power generation, water treatment, and pharmaceutical applications requiring reliable high‑accuracy temperature monitoring in harsh industrial environments.

The FBM37 provides 8 galvanically isolated input channels, each electrically separated from other channels and ground to eliminate ground loops and cross‑channel interference. It supports a wide range of RTD types: Pt100, Pt1000, Ni120, and Ni1000, with software‑selectable 2‑wire, 3‑wire, or 4‑wire sensor connections to match diverse installation requirements. This flexibility reduces the need for multiple specialized modules, simplifying system design and lowering inventory costs.

Delivering ±0.05% full‑scale accuracy and 16‑bit resolution, the FBM37 ensures precise temperature readings across industrial ranges. Each channel uses precision constant‑current excitation and built‑in linearization to compensate for sensor non‑linearity and lead‑wire resistance errors. With a low drift design and automatic ambient temperature compensation, the module maintains measurement stability over time, even in fluctuating environmental conditions, minimizing calibration frequency and ensuring long‑term reliability.

Each channel offers 1500 VDC isolation between field inputs and the DCS backplane, plus 600 V AC one‑minute withstand rating for channel‑to‑channel and channel‑to‑ground isolation. This robust isolation blocks common‑mode noise, prevents voltage spikes from damaging the module or DCS, and enhances safety for both personnel and equipment in electrically noisy industrial environments.

The FBM37 supports hot‑swap installation and replacement, allowing online maintenance without shutting down the process or disrupting other I/O modules. Communication with Foxboro FCP/ZCP controllers uses a redundant 2 Mbps HDLC fieldbus, providing error‑checked data transfer with automatic path failover. Redundant 24 VDC power input ensures continuous operation even if one power source fails, maximizing system uptime for critical processes.

Onboard LED indicators clearly display power status, communication health, and module‑level fault conditions for quick on‑site troubleshooting. Advanced diagnostics continuously monitor sensor open/short circuits, out‑of‑range signals, communication errors, and power supply anomalies, sending real‑time alerts to the DCS for proactive maintenance and rapid fault resolution. This reduces unplanned downtime and enhances system reliability.

Constructed with a conformal‑coated PCB and a rugged industrial housing, the FBM37 is certified for CE, UL, CSA, and ISA S71.04 Class G3 (harsh environment), ensuring reliable operation in non‑hazardous industrial settings. It operates stably in temperatures from 0 °C to +60 °C (storage: –40 °C to +85 °C), 5%–95% non‑condensing humidity, and moderate vibration/shock conditions. The compact form factor enables high‑density I/O packing in standard DCS cabinets, mounting directly on Foxboro I/A Series backplanes to save panel space.

Manufacturer: Foxboro (Invensys, now Schneider Electric)Compatible Systems: Foxboro I/A Series DCS, EcoStruxure Foxboro (Foxboro Evo™) DCSModel/Part Number: FBM37Module Type: 8‑channel isolated RTD temperature input interface moduleInput Channels: 8 fully isolated, software‑configurable channelsSupported RTDs: Pt100, Pt1000, Ni120, Ni1000; 2‑wire, 3‑wire, 4‑wire selectableResolution: 16‑bitAccuracy: ±0.05% full‑scaleIsolation: 1500 VDC (input‑to‑backplane); 600 V AC for 1 minute (channel‑to‑channel/ground)Update Rate: 100 ms per channelCommunication: Redundant 2 Mbps HDLC fieldbus (to FCP/ZCP controllers)Power Supply: 24 VDC (+5%/–10% tolerance), redundant inputPower Consumption: Max 2.8 WOperating Temperature: 0 °C to +60 °CStorage Temperature: –40 °C to +85 °CRelative Humidity: 5%–95% non‑condensingVibration: 0.1 g rms, 5–500 HzShock: 10 g, 20 ms half‑sineDimensions (W × H × D): Approximately 140 mm × 165 mm × 45 mmWeight: Approximately 0.6 kgCertifications: CE, UL, CSA, ISA S71.04 Class G3Reliability Features: Hot‑swap capable; redundant communication/power; full channel isolation; conformal‑coated PCB; comprehensive diagnostics.

The FBM37 is designed for high‑accuracy RTD‑based temperature monitoring in general‑purpose to critical industrial processes, where reliable, drift‑free measurements and flexible sensor compatibility are essential.

In chemical and petrochemical plants, it monitors reactor, distillation column, and heat exchanger temperatures using Pt100 or Pt1000 RTDs, supporting precise batch and continuous process control. The high accuracy ensures tight temperature control for quality‑critical reactions, improving product consistency and yield.

In oil and gas facilities—including refineries, gas processing plants, and offshore platforms—it tracks critical equipment temperatures such as furnace tubes, compressor bearings, and pipeline heat traces, ensuring safe and efficient operation in remote, noisy, and corrosive environments.

In power generation (thermal, combined‑cycle, and cogeneration plants), the FBM37 measures boiler, turbine, and generator winding temperatures with high precision, enabling condition monitoring and preventing overheating‑related failures. The stability ensures long‑term reliability in high‑temperature environments.

In water and wastewater treatment, it monitors digester, incinerator, and process water temperatures, supporting efficient biological treatment and regulatory compliance. The isolation protects against electrical interference from pumps and other equipment.

In pharmaceutical, food and beverage, and manufacturing, the module’s high accuracy and clean‑design compliance make it suitable for sanitary process temperature monitoring, such as in fermentation tanks, sterilization equipment, and HVAC systems, meeting strict industry standards for hygiene and precision.

The FBM37 mounts directly on standard Foxboro I/A Series backplanes inside DCS cabinets, connecting to dedicated baseplates for backplane power and redundant HDLC fieldbus communication. Field wiring terminates at mating termination assemblies (TAs) equipped with screw terminals, per‑channel fuses, and knife disconnect/test sockets for easy maintenance. TAs support 2‑wire, 3‑wire, or 4‑wire RTD connections and accommodate shielded RTD wiring to minimize noise interference.

Configuration is performed via Foxboro DCS software: select RTD type, choose wire configuration, set measurement ranges, configure filtering times, and map channels to DCS tags. The module is plug‑and‑play compatible with existing Foxboro systems, supporting hot‑swap replacement to minimize downtime. For high‑availability applications, redundant communication paths and power supplies can be configured to ensure continuous data transfer.

Routine maintenance includes visual inspection for physical damage, loose connections, or dust buildup on the module and termination assemblies, and verification of front‑panel LEDs for normal power and communication status. Periodic testing of measurement accuracy, sensor connection integrity, and redundant communication failover is recommended, especially in high‑vibration or corrosive environments. The conformal‑coated PCB reduces cleaning frequency and protects against moisture, dust, and chemical contaminants.

Faulty modules can be repaired by authorized Schneider Electric service providers, with standard repair options available. The FBM37 comes with a 12‑month standard warranty against manufacturing defects, with extended warranty options available for long‑term operational reliability。