Component Snapshot At-a-Glance

• Model:
• Alt. P/N: (official series designation, no alternate factory part marking)
• Product Series: Foxboro I/A Series 200 Compact FBM Baseplate Platform
• Hardware Type: Isolated RTD analog input field module
• Key Feature: 8 fully galvanically separated channels supporting 2/3/4-wire RTD wiring configurations
• Primary Field Use: Convert field RTD resistance readings to digital data for DCS temperature trending and PID control loops.

Hard-Numbers: Technical Specifications

• Protocol Support: Foxboro proprietary 2Mbps Modulebus backplane bus
• Port Count: 8 field terminal input channels, rear gold-finger backplane connector
• Baud/Data Rate: Fixed 2Mbps Modulebus communication speed
• Operating Temperature: -20°C ~ +60°C continuous cabinet ambient rating
• Isolation Rating: 1500VAC channel-to-backplane galvanic isolation per channel bank
• Power Draw: 3.1W nominal operating power from baseplate 24VDC SELV rail
• Single Channel Range: 0~320Ω input resistance span per RTD channel
• Sensor Excitation: Fixed 0.75mA DC constant current drive per individual channel
• Hot-Swap Rating: Live insert/extract permitted on energized 200-series compact baseplate
• Accuracy Grade: ±0.05% full span conversion error for standard Pt100 RTD sensors

The Real-World Problem It Solves

Unisolated shared RTD input boards pick up common-mode noise from nearby VFD and MCC cabling, drifting temperature PV values and triggering false high/low process interlock trips. Mixed 2/3/4-wire RTD field runs previously required separate signal conditioner panels that add extra marshalling points and potential open-circuit faults.Where you’ll typically find it:

• Refinery furnace tube skin and feed preheater bundle temperature monitoring racks
• Coal power plant boiler superheater/reheater tube surface temperature DCS input cabinets
• Petrochemical reactor vessel wall and jacket cooling water remote temperature I/O racks

Single slot baseplate mounting eliminates external signal conditioning hardware and suppresses cross-channel EMI drift entirely.

Hardware Architecture & Under-the-Hood Logic

This houses independent per-channel excitation and ADC circuitry, isolated via optocoupler stacks to split field sensor wiring and DCS backplane power domains; no user programmable onboard CPU, fixed ASIC handles resistance-to-digital conversion.

1. Rear edge gold-finger taps regulated 24VDC supply and raw Modulebus command data from host baseplate backplane.
2. Onboard circuit distributes fixed 0.75mA excitation current out each field terminal to connected RTD resistance sensor.
3. Channel ADC samples resultant voltage drop across RTD, converts measured ohm value into 16-bit digital temperature register data.
4. Isolation barrier blocks field-side ground potential shift and induced AC noise before digital data passes to Modulebus transceiver.
5. Transceiver packages aggregated 8-channel readings into standard Modulebus frame for uplink to host FCP controller via backplane.
6. Front panel LED array flags module power status, backplane bus activity, single-channel open wire and overall card fault conditions.

Field Service Pitfalls: What Rookies Get Wrong

Miswire 3-Wire RTD Compensation Lead Into Unused Channel Terminals

Tech routes RTD compensation wire across empty spare channel pins; stray channel leakage current skews measured resistance and creates constant 3~8°C fixed temperature offset.

• Quick Fix: Terminate all three 3-wire conductors exclusively to defined channel pin set; leave unused terminal blocks empty with no spare wiring jumpers.

Overdrive Channels With External Loop-Powered Transmitter Wiring

Improperly wire 4-20mA transmitters directly to RTD input terminals; excess loop current burns internal channel excitation resistors and permanently disables individual input bank.

• Field Rule: accepts only passive resistance-type RTDs; all powered transmitters route to separate FBM current input modules.

Ignore Cabinet Thermal Derating During High Ambient Heat

Install module inside sealed unventilated marshalling cabinet above +62°C ambient; internal ADC drift rises exponentially leading to slow creeping temperature PV drift over weeks of runtime.

• Field Rule: Derate operating ambient to max +55°C for fully populated baseplate; add cabinet exhaust fans when surrounding enclosure exceeds +50°C continuous.

Commercial Availability & Pricing Note

Please note: The listed price is for reference only and is not binding. Final pricing and terms are subject to negotiation based on current market conditions and availability.