Description
Product Overview
The Triconex 3301 is a single-channel, 24V DC digital input module for the Tricon Triple Modular Redundant (TMR) Safety Instrumented System (SIS) platform. It is a legacy, non-TMR (simplex) input module designed for applications where a single fault tolerant architecture is not required for the input signal, or for interfacing with non-critical status or permissive signals. Unlike the standard TMR modules (e.g., 3604E), the 3301 provides a single input path per point, making it a more cost-effective solution for monitoring non-safety or non-critical signals within a Tricon safety system, such as remote status indicators, mode selection switches, or other signals that do not initiate safety actions.
The core value of the Triconex 3301 lies in its ability to integrate non-critical signals into the Tricon I/O structure, simplifying system architecture and reducing cost while maintaining compatibility with the Tricon engineering and diagnostic environment. It allows engineers to bring auxiliary or informational signals into the same controller chassis that houses critical safety I/O, enabling a unified view of the process without the cost of triple-redundant hardware for every point. For system designers, the 3301 is a practical choice for monitoring those inputs where a single point of failure is acceptable, and the high availability of a TMR design is not justified. It is important to note that the use of a simplex I/O module like the 3301 in a safety loop will affect the overall Safety Integrity Level (SIL) rating of that loop, and its application must be carefully evaluated as part of the safety lifecycle.
Technical Specifications
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Parameter Name
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Parameter Value
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Product Model
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Triconex 3301
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Manufacturer
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Invensys Triconex (now Schneider Electric)
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Product Family
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Tricon Simplex (Non-TMR) Digital Input Module
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Primary Function
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16-point, 24V DC Single-Channel (Simplex) Digital Input Module
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Electrical Characteristics (Per Channel)
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Input Type: Sinking (Dry Contact) or Sourcing (Wet Contact) compatible. Typically used with switch or relay contact inputs.
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Input Voltage: Nominal 24V DC. Standard industrial control voltage.
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«ON» State Voltage: Typically > 10-15V DC to recognize a logical «1».
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«OFF» State Voltage: Typically < 5V DC to recognize a logical «0».
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Input Current: Typically 5-10 mA per point at 24V DC.
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Input Impedance: In the range of several kilo-ohms.
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Response Time: Typically in the millisecond range.
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Point Density: 16 points per module.Safety & Architecture
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Architecture: Single-Channel (Simplex). This is NOT a TMR module. Each field input is connected to a single input circuit. There is no internal voting or redundancy.
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Diagnostics: Basic diagnostics are present but are less comprehensive than TMR modules. Typically includes power supply monitoring and may include basic field status indication. It cannot perform channel-to-channel comparison for fault detection.
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Effect on Safety Loop: Using a simplex input in a safety instrumented function (SIF) will reduce the hardware fault tolerance and diagnostic coverage, impacting the achievable PFD and SIL rating. It is generally not used for primary safety sensors in a SIL 2/3 loop unless the overall architecture compensates for it elsewhere.Mechanical & Integration
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Form Factor: A module designed for installation in a Tricon I/O chassis. It is not hot-swappable in the same manner as newer TMR modules. Earlier versions may have a different form factor than the High-Density (HD) modules.
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Termination: Field wiring connects via a removable terminal block on the front of the module or through a connected terminator assembly.
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LED Indicators: Per-point status LEDs to indicate the ON/OFF state of each input.
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Compatibility: Designed to work with older Tricon chassis and main processors (e.g., Tricon v8, early v9 systems). It may require a specific I/O terminator or carrier.Environmental
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Operating Temperature: 0 to 60°C (32 to 140°F) typical for industrial environments.
Key Features and Advantages
Cost-Effective Integration of Non-Critical Signals: The primary advantage is economic. It allows a large number of status, permissive, or alarm signals to be brought into the Tricon system at a lower cost per point than using TMR modules, while still using the same controller, engineering tools, and operator interface.
Simplified System Design: Reduces the overall I/O module count and chassis size for a given number of points when many non-safety signals are required. Provides a clean, integrated solution within the Tricon hardware ecosystem.
Uses Standard Tricon Infrastructure: The module is configured, wired, and programmed using the same Triconex TriStation 1131 software and installed in a standard Tricon chassis alongside TMR modules. This simplifies training, spares holding, and maintenance.
Reliable Performance for Non-Critical Functions: While not fault-tolerant, it is a robust, industrially hardened module suitable for reliable monitoring of non-critical process states.
Application Areas
The Triconex 3301 is used in Tricon-based control and safety systems for monitoring signals that are not part of the primary safety instrumented functions (SIFs).
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Equipment Status Indication: Monitoring running/stopped status of pumps, fans, or other equipment (from auxiliary contacts) for sequence control or annunciation.
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Mode Selection and Permissives: Reading the position of maintenance/local/remote selector switches, permissive switches, or key locks.
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Alarm Annunciation (Non-Critical): Bringing in signals for general alarm lights or horns that are not part of the certified safety alarm system.
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Process Status Monitoring: Monitoring valve limit switch feedback for non-critical valves, tank level switches for inventory, etc.
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Interface to Non-Safety Systems: Bringing in status points from the Basic Process Control System (BPCS) or other subsystems for informational purposes in the SIS.
Related Products
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Tricon Chassis: Such as the legacy Tricon Chassis models (e.g., 10-slot chassis) compatible with this module type.
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Tricon Main Processor (MP): The main controller (e.g., MP 3008) that reads the input data from the 3301.
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I/O Terminator or Carrier Board: A separate termination unit or carrier that the 3301 module plugs into, which provides the field wiring terminals. The specific terminator model (e.g., 8301T) is required.
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Power Supply: The Tricon system power supply that provides power to the chassis and I/O modules.
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Triconex TriStation 1131: The configuration and programming software used to define the module in the hardware configuration and map the I/O points to variables in the application logic.
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TMR I/O Modules: Such as the 3604E (24V DC TMR DI) and 8312 (120V AC TMR DI) for critical safety inputs.
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