Foxboro P0931RQ Termination Assembly

The Foxboro P0931RQ, also cataloged as the P0931RQ Termination Assembly, operates as a dedicated hardware component for field wiring termination and physical signal routing within Foxboro I/A Series fieldbus communication networks. The unit interfaces directly with Fieldbus Modules via a designated Type 4 DIN FBM cordset cable configuration to establish point-to-point field connectivity.

Hardware Specifications

Galvanic Isolation and Signal Routing

The P0931RQ establishes channel-to-channel and channel-to-system galvanic isolation pathways across all 32 processing points. This architecture isolates loop-powered instrumentation networks from core system electronics, suppressing common-mode noise and breaking ground loop currents across the 4-20 mA HART loop protocol paths.

The onboard passive circuit traces route variable current and voltage loops through localized surge suppression components to clamp transient voltage spikes. This signal-to-system partitioning guarantees that high-voltage spikes introduced on the field-side terminal blocks cannot migrate through the Type 4 DIN FBM cable connector to cause catastrophic failure on adjacent control processing components.

Frequently Asked Questions

Q: Can the DIN FBM cordset cable be disconnected from the P0931RQ while field sensors are live? A: Yes. The passive design allows the Type 4 DIN FBM cordset cable to be decoupled from the termination assembly for loop isolation without risking damage to the passive component itself. However, proper care must be taken to ensure that un-terminated field loops do not short-circuit against adjacent chassis metalwork.

Q: Does the P0931RQ supply auxiliary power to 2-wire transmitters? A: The assembly provides integrated distribution channels for redundant 24 VDC bus inputs. When connected to a compatible power rail, it routes loop power to active 4-20 mA transmitters via the designated field termination screws.

Q: Is there any software configuration required for the P0931RQ inside the I/A Series DCS? A: No. The P0931RQ functions entirely as a passive physical interface and surge suppression routing plane. The DCS identifies only the hosting active Fieldbus Module (FBM), while the baseplate and termination assembly remain transparent to the software environment.

Field Installation Guidelines

• DIN-Rail Mounting Stability: Snaps securely onto standard 35 mm DIN-rails. Verify that the grounding clip on the rear of the assembly establishes firm, paint-free mechanical contact with the structural metal rail to guarantee a low-impedance path to ground for the surge protection diodes.
• Shield Grounding and Drain Wire Termination: Field instrument shield wires must be terminated to the designated ground bus bar within the enclosure. Do not daisy-chain shield drain connections across adjacent terminals; maintain point-to-point isolation to minimize EMI/RFI noise penetration.
• Terminal Screw Torque Specifications: Tighten all field-side terminal block screw connections to a maximum torque of 0.5 N-m to prevent mechanical degradation of the internal printed circuit board solder joints.
• Cable Routing Separation: Route the high-density Type 4 DIN FBM cordset cable separately from high-voltage AC motor lines or switching inductive loads to prevent inductive noise injection into low-level analog channels.