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3721 Other Names:
Redundant Module 3721
3721 Controller Module
Analog Module 3721
Input Characteristics: 32 differential input channels, supporting 0-5V DC or -5 to +5V DC voltage range, programmable resolution of 12-bit or 14-bit, input update rate of 10ms. Accuracy up to 0.15% of FSR (0-60℃), common-mode rejection -85 dB (DC-100Hz).
Protection and Isolation: 150 VDC/115 VAC continuous over-range protection, branch-to-branch isolation resistance 420 kΩ, power-off resistance 140 kΩ (typical DC value), compliant with TMR architecture requirements.
Physical Parameters: Module weight 1.36 kg, transport weight 4 kg, yellow marking (distinguishing it from the 3720 model), equipped with PASS/FAULT/ACTIVE/FIELD diagnostic indicators, operating temperature -20℃~+60℃, storage temperature -40℃~+85℃.
Core Functions and Architecture
Safety Certification: Compliant with IEC 61508 and IEC 61511 standards, SIL3 safety level certification, suitable for high-safety-requirement scenarios such as petrochemical, oil and gas, and power industries (e.g., ESD, F&G, BMS systems).
Redundancy Design: Employs a 2003 (three-out-of-three) voting mechanism, with three independent CPUs running in parallel, supporting hot-swapping, single-point failure does not affect system safety operation, and has an extremely long mean time between failures (MTBF). Communication and Integration: Supports TriStation 1131 programming software (IEC 61131-3 standard language), compatible with Modbus TCP/IP, RS-232/485 protocols, and can be seamlessly integrated with Tricon series I/O modules (such as 3503E, 3660).
Safety and Reliability Advantages:
Safety Certification: Meets SIL3 safety level, certified by IEC 61508/61511, suitable for high-risk industries such as nuclear power and oil and gas. For explosion-proof scenarios, ATEX/NEPSI certification is required.
Diagnostic Capabilities: Built-in self-diagnostic function can detect CPU, memory, and bus faults, quickly locating problems through LED status indicators (such as RUN/READY/FAULT). System status monitoring and fault analysis are achieved using Enhanced Diagnostic Monitor (EnDM) software.
Environmental Adaptability: Operating temperature -40°C to +70°C, storage temperature -40°C to +85°C, IP20 protection rating (IP54 optional), meets EMC immunity requirements.
Application Scenarios
Industrial Automation: Used for production line equipment coordination and process parameter monitoring (such as temperature, pressure, flow rate), widely used in petrochemical, power, water treatment, and pharmaceutical industries.
Safety Systems: Integrated into emergency shutdown (ESD) and fire and gas detection (F&G) systems to ensure real-time monitoring of critical process parameters and fault-tolerant response.
Remote Monitoring: Supports expansion chassis (RXM) for remote I/O module connections within 7.5 miles (12 kilometers), suitable for linkage between distributed control systems (DCS) and SIS.
Nuclear Energy: In the digital transformation of the Daya Bay Nuclear Power Plant, the TRICONEX system (including module 3721) upgraded the control system, supporting remote I/O expansion (within 12 kilometers) and intelligent IoT data acquisition, improving unit reliability and reducing operation and maintenance costs.
Petrochemical and Power Applications: Enables high-precision signal acquisition in equipment such as reactors, distillation towers, and generators, with a TMR architecture ensuring that single-point failures do not affect system operation.
Special Scenarios: Supports expanded chassis for distributed control, suitable for long-distance monitoring scenarios such as oil and gas pipelines and new energy grid connection.
Installation and Maintenance:
Configuration Requirements: Must be installed in a Tricon rack (e.g., 8008/8011), supports hot-swapping, mechanical keying of module slots to prevent misinsertion, and uses Enhanced Diagnostic Monitor for fault diagnosis and clearing.
Diagnostic Functions: Built-in self-diagnostic capabilities detect CPU, memory, and bus faults, and quickly locate problems through LED status indicators (e.g., RUN/READY/FAULT).
Maintenance Recommendations:
Regularly use TriStation software for configuration and self-diagnosis, checking signal integrity and redundant module switching functionality.
Follow SIL3 level maintenance standards, including regular calibration (zero/range), spare parts management, and cross-leg register fault troubleshooting.
Troubleshooting: By combining LED indicators with diagnostic software, potential problems can be quickly located and resolved, such as intermittent faults like Register Ox79 test failures.
Latest Application Cases and Performance Comparison
Nuclear Energy Innovative Application: In the Tianwan Nuclear Power Plant’s “Heqi-1” project, the TRICONEX system (including the 3721 module) is used for real-time monitoring of the nuclear steam supply project, ensuring the safety and efficiency of industrial steam supply, reducing carbon emissions by 700,000 tons annually, and saving 400,000 tons of raw coal.
Performance Comparison: Compared to similar products (such as Siemens and Yokogawa), the 3721 module performs superiorly in terms of accuracy, redundancy design, communication protocol compatibility, and adaptability to harsh environments. It supports multiple protocols (such as EtherCAT and Modbus TCP) and flexible expansion to meet the needs of applications of different scales.
Compatible Modules in the Same Series
Analog Input Modules:
TRICONEX 3720: Supports 64 single-ended input channels, voltage range 0-5V or -5 to +5V, complementing the 3721’s differential/single-ended signal capabilities, suitable for various signal acquisition scenarios.
TRICONEX 3704E: 64-channel analog input, supports 0-5V/0-10V voltage range, 75ms update rate, suitable for applications requiring higher channel density.
TRICONEX 3708E: Thermocouple input module, supports J/K/T/E type thermocouples, compatible with cold junction compensation, suitable for temperature monitoring scenarios.
Digital I/O Modules:
TRICONEX 3503E/3625: Digital input/output modules, support 24V DC signals, suitable for switch control and status feedback.
TRICONEX 3664: 24V DC digital output module, supports redundant output, suitable for actuator control.
TRICONEX 3005/3006/3007: Supports Triple Modular Redundancy (TMR) architecture, with three independent CPUs operating in parallel, supporting hot-swapping and fault switching to ensure that a single point of failure does not affect the safe operation of the system.
TRICONEX 4351B/TCM-4351B: Supports Modbus TCP/IP, Ethernet/IP, and other protocols, enabling communication with host computers, DCS systems, or industrial IoT platforms.
TRICONEX 4108 (EICM): Enhanced intelligent communication module, supporting high-speed redundant network communication, suitable for distributed control systems.
TRICONEX 3708E/3720: Thermocouple/analog input module, enabling remote signal acquisition through the RXM chassis, extending the system coverage.
Potential Issues and Precautions
Environmental Adaptability: Avoid environments with strong electromagnetic interference and ensure compliance with EMC protection requirements. Storage temperature: -40℃~+85℃; Operating temperature: -20℃~+60℃.
Frequently Asked Questions: Some models may experience intermittent cross-leg register failures (such as Register 0x79 test failure), but this does not affect basic safety functions and can be troubleshooted using diagnostic tools.
Summary: The TRICONEX 3721 analog input module, with its high precision, high reliability, and triple redundancy design, has become a core component in the industrial safety field. Its powerful diagnostic capabilities and flexible integration ensure stable operation and rapid fault response in harsh environments, making it the preferred solution for high-risk industries such as petrochemicals and power generation.
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Triconex 3721 Frequently Asked Questions
Is it hard to find 3721 units?
Some of the parts on Triconex Parts can be very difficult to find. A great deal of them have reached end-of-life status and are therefore no longer in production. Aotewell Automation will make every effort to locate the 3721 in response to your quote request, and we will be able to get you better pricing if no one stirs up the market.
What is meant by “stir up the market”? Why is it a problem?
Stirring up the market is the result of many different suppliers all receiving requests to locate a certain part. It makes other suppliers believe the part is in much higher demand than it might actually be, resulting in raised prices and lower availability. To keep costs down and ensure a smooth transaction, Aotewell Automation recommends requesting quotes from suppliers in a limited, stragegic manner.
When should I expect to receive the 3721?
The 3721’s availability will be the primary determining factor for lead time. We will check with our trusted suppliers in the event that we do not currently have the 3721 in our inventory. Lead time may also be affected by additional services performed, such as repair or refurbishment.
How does Triconex Parts ship the 3721?
We make most of our shipments via FedEx, UPS, DHL, and USPS, and we are prepared to use your preferred carrier or account. International (non-USA) shipments are not a problem.
https://www.weikunfadacai1.com/product/triconex-3721/
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The TRICONEX 3721 Analog Input Module supports a voltage range of 0-5V DC or -5 to +5V DC, 32 differential input channels, DC coupling, an input update rate of 10ms, programmable resolution of 12-bit or 14-bit, accuracy up to 0.15% of FSR (0-60℃), and common-mode rejection of -85 dB (DC-100Hz). It features 150 VDC/115 VAC continuous over-range protection, 420 kΩ inter-branch isolation resistance, and 140 kΩ power-off resistance (DC typical), meeting TMR (Triple Modular Redundancy) architecture requirements. It supports TriStation 1131 programming software (IEC 61131-3 standard language), is compatible with Modbus TCP/IP, RS-232/485 protocols, and can be seamlessly integrated with Tricon series I/O modules (such as 3503E and 3660). Used for production line equipment coordination and process parameter monitoring (such as temperature, pressure, and flow), it is widely used in industries such as petrochemicals, power, water treatment, and pharmaceuticals. It supports expansion chassis (RXM) for remote I/O module connections within 7.5 miles (12 kilometers), suitable for linkage between distributed control systems (DCS) and SIS. Integrated into emergency shutdown (ESD) and fire and gas detection (F&G) systems, it ensures real-time monitoring of critical process parameters and fault-tolerant response.
admin –
https://www.weikunfadacai1.com/product/triconex-3721/