Core Advantages

Universal channel design. Each of the 40 channels can be freely configured into five modes: digital input, digital output, 4–20 mA analog input, fire circuit, and valve monitoring circuit. Multiple signal types can coexist on one assembly, reducing the quantity of termination bases inside cabinets and saving cabinet installation space.

Grouped power supply architecture. The 40 channels are divided into 5 groups of 8 channels each. Every group is equipped with independent dual redundant 24 VDC power supply plus anti-backfeed diode isolation. The first channel of each group can be set as a controllable power output to remotely cut off and reset fire detector circuits without additional external relays.

Two types of standard resistors embedded on PCB: high-power 7 W 250 Ω current-limiting resistors and high-precision 0.1% 250 Ω sampling resistors. No external conversion resistors are required for analog signal acquisition; automatic current limiting protects field instruments and back-end safety modules in case of circuit short-circuits.

Standard industrial mounting construction, compatible with TS32 and TS35 standard DIN rails, supporting both horizontal and vertical installation. All terminals, fuses and jumpers are front-accessible, eliminating equipment disassembly during field wiring, configuration and maintenance.

Graded channel protection with three types of pluggable TE5 series fuses: 50 mA for analog circuits, 315 mA for digital inputs, and 2 A for digital outputs. Independent fusing protection per channel ensures faults on a single loop do not interrupt signals of the entire group.

Wide temperature and humidity adaptability. Continuous operation from 0 °C to 60 °C; storage and transportation range from -25 °C to 70 °C; operable under 10%–95% non-condensing humidity, suitable for outdoor explosion-proof cabinets and indoor central control cabinets.

Model Breakdown

Full part number: PD-T8842

PD: Prefix for termination base products of Rockwell Trusted safety systems

T8842: Hardware model, representing the versatile universal VFTA field termination assembly

VFTA: Abbreviation for Versatile Field Termination Assembly, differentiating it from ordinary single-function FTA termination bases and indicating fully reconfigurable input/output channels

T8842 has no sub-models. It is factory-supplied with a full set of 50 mA / 315 mA / 2 A TE5 fuses, with no optional hardware variants. All functional configurations are implemented solely through jumper and fuse combinations.

Core Specifications

Channel Configuration

40 channels per unit split into 5 power groups of 8 channels each. Each group has dual redundant 24 VDC power supply; maximum group supply current 2.52 A; total load limit 8 A for 8 output channels per group.

Signal Compatibility

Active digital input, line-monitored passive digital input, digital output, 4–20 mA current-source analog input, fire detection circuits, and mixed valve position monitoring circuits.

Wiring Terminals

Field instrument terminals TB1–TB40 are all 3-pin terminals (field power, signal, 0 V). Module-side connection: 5 sets of 10-pin terminals TBG1–TBG5. Power interfaces: 5 sets of 4-pin terminals TBFP1–TBFP5.

Protection Components

On-board integrated 250 Ω power resistors and 250 Ω high-precision sampling resistors; pluggable TE5 fuses providing independent per-channel fuse protection.

Mechanical Mounting Dimensions

Height: 110 mm; width: 360 mm; depth including rail connector: 68 mm; total weight: 950 g; maximum power consumption: 9 W.

Safety Compliance

Compatible with Trusted system firmware V3.6.1 and above; supports intrinsically safe explosion-proof circuit wiring; complies with hardware design specifications for SIF safety instrumented functions.

Circuit Limits

Maximum current limit per 24 V channel: 96 mA. Valve monitoring circuits support multi-tap resistive limit switch acquisition to identify fully open, half-open and fully closed valve positions, with built-in open/short circuit fault diagnostics.

Applicable Industries

Petrochemical Refining: Flammable gas detection circuits for heating furnaces and distillation columns, monitoring and output loops for emergency shutdown valves

Oil & Gas Production: Signal transition for wellhead fire detectors, downhole combustible gas probes and underground safety shutdown valves

Fine Chemical Processes: SIS safety instrumented systems for reactors, toxic gas detection, and control loops for emergency shutdown valves

Oil & Gas Storage & Transportation: Flame/gas detectors in tank farms and monitoring/output circuits for tank emergency isolation valves

Power & Coal Chemicals: Fire alarm circuits for coal gasification plants and monitoring systems for process safety shutdown valves

Hazardous Pharmaceutical Workshops: Termination bases for safety interlock instrumentation on toxic medium reaction units