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Product Introduction
The Honeywell 2MLI-D21D Digital Input Module is an industrial-grade digital input unit designed to be a part of Honeywell’s reliable and high-performance automation and control systems. Engineered to provide accurate signal detection and seamless communication with programmable logic controllers (PLCs) and distributed control systems (DCS), this module stands out for its dependable operation even in harsh industrial environments.
As part of Honeywell’s Modular I/O (MLI) product line, the 2MLI-D21D module supports 24V DC digital inputs and is well-suited for discrete input applications in industries such as oil & gas, power generation, chemical processing, and manufacturing automation. It provides robust signal isolation, real-time diagnostic features, and ease of integration into existing control infrastructures.
Technical Specifications
| Parameter | Description |
|---|---|
| Model | 2MLI-D21D |
| Manufacturer | Honeywell |
| Input Type | Digital (Discrete) |
| Number of Channels | 16 digital input channels |
| Input Voltage Range | 24V DC nominal (with tolerances typically from 18–30V DC) |
| Input Current | Approx. 3.2 mA per channel |
| Isolation | Channel-to-bus isolation via opto-isolators |
| Input Signal Delay | Typically <10 ms |
| Diagnostics | Channel-wise status indication and fault detection |
| Power Consumption | Approx. 5W |
| Operating Temperature | -20°C to +60°C |
| Storage Temperature | -40°C to +85°C |
| Humidity | 5% to 95% non-condensing |
| Mounting Type | DIN rail or panel mounting |
| Communication Interface | Backplane bus via I/O base |
| Dimensions (W x H x D) | 135 x 115 x 30 mm |
| Weight | 0.17 kg |
| Compliance / Certifications | CE, UL, CSA, RoHS compliant |
Applications
The 2MLI-D21D module finds application in a wide range of industrial sectors where real-time monitoring and status detection of digital devices is critical. Its versatility makes it ideal for:
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Factory Automation Systems: Monitoring limit switches, proximity sensors, and push buttons.
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Process Control Systems: Capturing ON/OFF states of pumps, valves, and actuators.
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Power Plants: Monitoring digital status signals in turbine and generator control systems.
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Oil & Gas Facilities: Digital signal acquisition in hazardous area systems with intrinsic safety barriers.
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Water & Wastewater Treatment: Controlling remote inputs from field instrumentation and actuators.
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Building Management Systems (BMS): Interfacing with HVAC units and security systems.
Product Advantages
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High Reliability: Designed for continuous operation in harsh industrial environments.
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16 Channel Density: High-density module reduces the number of units required, saving cabinet space.
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Electrical Isolation: Opto-isolation ensures protection from field-induced electrical noise.
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Plug-and-Play Design: Easily integrates with Honeywell’s Experion and other DCS/PLC systems.
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Advanced Diagnostics: Built-in fault detection for rapid troubleshooting.
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Industrial Durability: Operates across a wide temperature range with vibration tolerance.
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Modular Architecture: Scalable for expanding I/O needs without replacing existing setups.
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Regulatory Compliance: Meets global standards for safety and emissions.
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Low Power Consumption: Energy-efficient design supports long-term sustainability goals.
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Maintenance-Friendly: LED status indicators and tool-free module replacement minimize downtime.
Frequently Asked Questions (FAQ)
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What voltage does the 2MLI-D21D Digital Input Module support?
It supports a nominal 24V DC input, with a typical range between 18V and 30V DC. -
Can I use this module in a high-temperature environment?
Yes, it operates efficiently in environments ranging from -20°C to +60°C. -
Is the module compatible with Honeywell’s Experion PKS system?
Absolutely. It is designed to integrate seamlessly with Experion and other Honeywell control systems. -
Does this module provide galvanic isolation?
Yes, each channel is opto-isolated to ensure electrical protection. -
What is the physical size of the module?
The dimensions are 135 x 115 x 30 mm. -
Is it suitable for marine or offshore applications?
While not marine-certified by default, it can be used in offshore environments if housed appropriately. -
Can I mount the module directly on a DIN rail?
Yes, it supports both DIN rail and panel mounting. -
How many digital input channels does it support?
It has 16 digital input channels. -
Are there LED indicators for each input channel?
Yes, each channel has a dedicated status LED for monitoring input state. -
What happens if one channel fails?
The system can detect and report the fault, allowing continued operation of the remaining channels.
Related Models from the Same Series or Category
| Model Number | Description | Input Type | Channels | Dimensions (mm) | Weight |
|---|---|---|---|---|---|
| 2MLI-D22D | Digital Input Module, Isolated | Digital | 16 | 50 x 130 x 120 | 0.45 kg |
| 2MLI-R11A | Relay Output Module | Relay | 8 | 50 x 130 x 120 | 0.48 kg |
| 2MLI-A41B | Analog Input Module | Analog | 8 | 50 x 130 x 120 | 0.46 kg |
| 2MLI-D21F | Fast Digital Input Module | Digital | 16 | 50 x 130 x 120 | 0.45 kg |
| 2MLI-D24D | Digital Input Module with Diagnostics | Digital | 32 | 100 x 130 x 120 | 0.60 kg |
| 2MLI-PWR01 | Power Supply Module for MLI System | Power | — | 60 x 130 x 120 | 0.50 kg |
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|---|---|---|---|---|---|
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