2. Model Definition

51304685: Base model for 16-channel non-isolated HART analog input FTA

-250: Heavy-duty reinforced PCB protection grade

Multi-layer thick reinforced full-board conformal coating with superior resistance to high humidity, heavy dust and moderate corrosive chemical vapors

Upgraded high-energy composite bidirectional TVS surge stack, higher transient withstand energy than -200 and lower suffixes

Three-stage symmetrical cascaded RC differential EMI filter, tuned for extreme high-noise zones with massive VFD clusters and large motor control centers, no attenuation to HART carrier

Global common ground bus for all 16 channels, no independent galvanic isolation barriers

Extra-precision tight-tolerance isolated series current limiting resistors for perfectly uniform short-circuit overload protection across all 16 channels

Extra-wide thickened plastic channel baffles to eliminate inter-channel analog leakage and HART signal crosstalk

3. Technical Specifications

Channel Count: 16 common-ground channels, no per-channel galvanic isolation

Compatible Field Devices

Two-wire HART smart transmitters: pressure, differential pressure, mass/vortex/turbine flow, radar/float level, RTD/TC temperature, pH, ORP, dissolved oxygen, conductivity analytical transmitters

Backward compatible with conventional non-HART 4–20mA two-wire transmitters

FTA Structure: Passive non-isolated termination board with no internal power supply; integrated per-channel HART coupling, three-stage symmetrical filtering, high-energy surge protection and precision short-circuit current limiting

PCB Protection: Multi-layer thick reinforced conformal coating; flammability UL94 V0

Terminal Type: Compression screw terminals, fit solid/stranded copper wire up to 14 AWG; each channel has independent Ch+ / Loop– terminal pair sharing unified ground bus

Form Factor: Standard B-size footprint, snap-on installation for 35 mm standard DIN rails

Operating Ambient: 0℃ ~ +60℃ indoor control cabinet; humidity, dust and moderate corrosion tolerance surpasses -200 and lower grades; not certified for continuous salt fog (select -325/-375 for coastal/offshore salt fog environments)

Circuit Architecture Parameters

Three-stage symmetrical low-pass differential filtering, precisely calibrated to suppress severe industrial EMI without distorting HART waveform or analog 4–20mA signal

Composite high-energy bidirectional TVS stack suppresses positive/negative transient high voltage on every shared-ground input loop

Shared common ground design; ground potential difference between field and DCS triggers measurement drift and unstable HART communication

Ultra-tight tolerance current-limit resistors fully protect transmitters and IOP high-impedance inputs from short-circuit burnout

Extra-thick baffles fully block inter-channel analog bleed and cross-channel HART interference

Redundancy Support: Fully compatible with primary/standby redundant non-isolated HART AI IOP; hot-swap FTA replacement allowed without process shutdown

Approximate Unit Weight: 0.361 kg

4. Interface & Communication Configuration

Inner IOP Connection: Locking heavy-duty flat ribbon cable directly mates to non-isolated HART AI IOP pin headers. Reinforced multi-point cable strain relief prevents pin header deformation or fracture under sustained tension of long multi-core field instrument wiring harnesses.

Field Outer Terminals: Independent Ch+ / Loop– terminals for each two-wire transmitter loop; all loops share one unified ground bus aligned with DCS control ground potential.

Signal Mechanism: 4–20mA DC analog measurement signals overlaid with FSK HART digital signals via frequency division; low-distortion passive HART coupling integrated per channel.

HART Access: No dedicated auxiliary communication port; handheld HART communicator clamps directly across Ch+ and Loop– field terminals for commissioning, calibration and diagnostic data reading.

5. Core Functions

Common-ground mixed HART/standard signal transmission: Cost-effective single-ground layout supporting mixed deployment of HART smart and conventional 4–20mA transmitters.

Three-stage symmetrical heavy EMI noise rejection: Suppresses intense electromagnetic interference from large VFD systems, MCCs and medium-voltage switchgear to eliminate measurement jitter, fluctuation and frequent HART communication retries.

High-energy surge & short-circuit fault protection: Withstands lightning-induced line transients, equipment startup surges and field short-circuit high voltage to protect sensitive costly IOP high-impedance input semiconductors and field transmitters.

Heavy-duty uniform loop overload safeguarding: Precision matched current limiting prevents transmitter damage under accidental field wiring short conditions across all channels evenly.

Consistent channel linearity & HART synchronization: Ultra-precision matched passive components deliver identical measurement response and stable HART handshake across all 16 channels to reduce bulk calibration workload.

Redundant hot-swappable operation: Seamlessly follows primary/standby IOP switching logic; single-channel disconnection and troubleshooting do not impact operation of remaining 15 measurement loops.

6. Application Scenarios

Applicable Industries

Petrochemical complexes, heavy chemical synthesis plants, combined heat & power generation stations, large oil & gas refineries, pulp & paper mills, high-humidity industrial wastewater treatment, medium-to-high humidity pharmaceutical batch manufacturing lines

Typical Measurement Loops

Emergency safety shutoff system pressure/DP HART transmitters

High-volume heavy-duty process flow HART transmitters

Large vertical storage tank HART level transmitters

Furnace/reactor high-temperature RTD/TC HART transmitters

Moderately corrosive media pH/DO/conductivity HART analytical transmitters

Ideal for single-ground plant layouts, VFD-dense process areas, cabinets with persistent high humidity and heavy dust accumulation, and atmospheres containing moderate acidic/alkaline volatile vapors. Not suitable for offshore platforms or coastal sites with continuous salt fog exposure; upgrade to -325/-375 ultra-heavy-duty grades for those extreme environments.

7. Wiring Standards

Two-wire transmitter wiring: Transmitter positive → FTA Ch+, transmitter negative → FTA Loop– (shared ground bus); reversed polarity generates measurable PV offset and degraded HART waveform integrity.

Cable specification: Shielded twisted-pair instrument cable for all field wiring runs; cable shield grounded solely at DCS cabinet FTA side with field equipment end ungrounded to fully suppress ground loop noise.

Power cable segregation: Physically separate analog instrument cables from high-voltage AC power, MCC and VFD output wiring to minimize capacitive and inductive EMI coupling interference.

8. Incompatible Hardware

All isolated AI/AO FTAs (51304644, 51304640, 51304648, 51304650), non-isolated non-HART AI (51304672), non-isolated AO FTAs, discrete DI/DO termination boards, TC/RTD dedicated FTAs, pulse counter termination blocks and serial communication terminal assemblies cannot be paired with this non-isolated HART AI IOP card.