TRICONEX AIH 3723X Analog Input Module – Ensuring Industrial System Security and Stable Data Transmission!

Description

Product introduction

The TRICONEX AIH 3723X is a high-density, triple modular redundant (TMR) analog input module designed for use in legacy Triconex Mark V safety instrumented systems (SIS). As a critical component in high-integrity process control environments, the AIH 3723X provides 32 fully redundant analog input channels, enabling the acquisition of signals from field devices such as pressure transmitters, temperature sensors, level transmitters, and flow meters. Engineered for mission-critical applications, this module ensures continuous, fault-tolerant operation by leveraging Triconex’s patented TMR architecture, which allows the system to detect and compensate for hardware faults without interrupting process safety functions.

The AIH 3723X supports a wide range of analog signal types, including 4–20 mA current loops, ±10 V voltage inputs, thermocouples, and RTDs (resistance temperature detectors), making it highly versatile for diverse measurement requirements in complex industrial processes. It interfaces seamlessly with the TriBus communication network, ensuring high-speed, deterministic data transfer between the three independent processor legs of the Tricon system. With robust 2300 V AC isolation and advanced signal conditioning, the AIH 3723X maintains signal integrity in electrically noisy or hazardous environments such as offshore platforms, refineries, and chemical plants. Its integration with Tristation 1131 software enables efficient configuration, diagnostics, and maintenance, supporting long-term system reliability.

AIH 3723X TRICONEX

Core advantages and technical highlights

High channel density with TMR reliability:
The TRICONEX AIH 3723X delivers 32 analog input channels in a single module slot, significantly increasing I/O density compared to earlier models like the AI845 or AI855. This high-density design reduces chassis space requirements and system footprint, which is particularly beneficial in space-constrained or retrofit applications. Despite its compact size, the module maintains full triple modular redundancy—each channel is independently processed across three legs, enabling real-time voting and fault detection, essential for SIL 3 compliance per IEC 61508.

Universal input flexibility:
One of the key strengths of the AIH 3723X is its support for multiple signal types within the same module. Engineers can configure individual channels for 4–20 mA, voltage, thermocouple, or RTD inputs without requiring separate specialized modules. This flexibility simplifies system design, reduces spare part inventory, and lowers engineering costs in mixed-signal applications such as turbine monitoring, reactor control, and flare management systems.

Robust isolation and noise immunity:
With 2300 V AC isolation between field circuits, logic, and individual channels, the AIH 3723X effectively prevents ground loops, electrical surges, and electromagnetic interference—common challenges in high-power industrial environments. Its built-in filtering, transient protection, and cold-junction compensation (for thermocouples) ensure accurate and stable signal acquisition, even under harsh operating conditions.

Advanced diagnostics and hot-swap capability:
The module continuously performs self-diagnostics, monitoring for open wires, over-range conditions, calibration drift, and internal hardware faults. Diagnostic status is reported via the TriBus network and can be accessed through Tristation or third-party asset management systems. The AIH 3723X supports hot-swap replacement, allowing maintenance personnel to replace a faulty module without shutting down the process—critical for continuous operations in oil & gas, power, and chemical industries.

Backward compatibility and proven reliability:
As a core I/O module in the Triconex Mark V platform, the AIH 3723X is fully compatible with legacy Tricon systems using 8008/8009 chassis and 3503/3504/3507E processors. It has been deployed for decades in some of the world’s most demanding safety-critical facilities, earning a reputation for durability, stability, and long service life.

Typical application scenarios

The TRICONEX AIH 3723X is widely used in safety-critical control systems where high analog I/O density and fault tolerance are essential. In offshore oil and gas production facilities, it is commonly deployed in emergency shutdown (ESD) and fire & gas (F&G) systems to monitor wellhead pressures, separator levels, gas detection readings, and jacket stress on platforms. Its TMR architecture ensures that a single-point failure will not compromise safety system integrity, meeting API and IEC regulatory standards.

In gas turbine and steam turbine control applications, the AIH 3723X interfaces with vibration sensors, bearing temperature probes (via RTD), and fuel flow transmitters, providing real-time health monitoring for rotating equipment. Its ability to handle both temperature and process signals in one module makes it ideal for turbine protection systems (TPS) in power plants and LNG facilities.

Refineries and petrochemical plants utilize the AIH 3723X in furnace management systems (FMS), reactor interlocks, and distillation column control, where precise analog input is required for temperature, pressure, and level safety functions. Additionally, it plays a key role in cryogenic process monitoring in LNG liquefaction and storage units, where accurate temperature measurement is critical for process efficiency and safety.

Even as newer Tricon v10 systems adopt modules like the AI6700 and AI6800, the AIH 3723X remains in active service across thousands of installations worldwide, particularly in brownfield sites where legacy Mark V systems continue to operate reliably.

Related model recommendations

AI6700 – Modern analog input module for Tricon v10 systems; recommended for new installations or system upgrades.
AI6800 – High-density analog input module (32 channels) for Tricon v10, successor to the AIH 3723X in newer platforms.
AI855 – Predecessor analog input module with lower channel density; the AIH 3723X offers improved performance and scalability.
AOH 3723X – Complementary high-density analog output module for Mark V systems, often used with AIH 3723X in control loops.
DIH 3723X – High-density digital input module for Mark V, suitable for mixed I/O safety applications.
8008 / 8009 Chassis – 7-slot Triconex chassis designed for AIH 3723X installation in Mark V systems.
3503E / 3504E / 3507E – Main TMR processors compatible with AIH 3723X in legacy Triconex systems.
MM3723X – Mainframe module for Mark V systems, providing backplane communication and power distribution for AIH 3723X and other I/O.

AIH 3723X TRICONEX

Installation preparation

Before installing the AIH 3723X, ensure the Triconex chassis (e.g., 8008 or 8009) is powered down and properly grounded to prevent electrostatic discharge (ESD) damage. Verify that the system firmware and Tristation version are compatible—Tristation 5.1 or later is typically required. Insert the module into the designated I/O slot, ensuring full engagement with the backplane and secure locking mechanism.

Use shielded, twisted-pair cables for all field wiring, and terminate cable shields at the marshaling cabinet (single-point grounding) to minimize noise pickup. Connect field devices according to approved loop diagrams, observing correct polarity for 4–20 mA signals and avoiding shared grounds. Utilize the module’s removable terminal block for simplified wiring and future maintenance. After installation, power up the system and verify module status via LED indicators: a steady green “PASS” on all three legs indicates successful initialization. Confirm TriBus communication and voting status in Tristation 1131.

Maintenance suggestions

Perform regular visual inspections of the AIH 3723X for dust accumulation, moisture, or signs of corrosion, especially in offshore or high-humidity environments. Monitor diagnostic data in Tristation or asset management systems for early warnings such as open circuits, signal drift, or channel mismatches. Conduct periodic calibration checks using certified test equipment to ensure measurement accuracy.

The AIH 3723X supports hot-swap replacement—failed modules can be replaced without shutting down the process. Always store spare modules in anti-static packaging and in a temperature-controlled environment to ensure long-term reliability. Keep firmware and configuration backups up to date to facilitate quick recovery in case of failure.