A-B 1756-DMD30A | 30-Channel Digital Input Module
Product Overview
The A-B 1756-DMD30A is a high-performance digital input module engineered exclusively for Allen-Bradley’s ControlLogix 5000 programmable logic controller (PLC) series— a flagship platform for large-scale industrial automation, process control, and critical infrastructure applications. Designed to deliver reliable, high-density digital input acquisition, the A-B 1756-DMD30A enables the ControlLogix system to monitor 30 discrete input signals from field devices (e.g., limit switches, proximity sensors, pushbuttons) with exceptional accuracy and speed. Key features include 30 independently configurable input channels, built-in advanced diagnostics, wide voltage compatibility, and rugged industrial construction—making the A-B 1756-DMD30A indispensable for applications like automotive manufacturing lines, oil and gas pipeline control, and water treatment plant monitoring. Compliant with global industrial standards (e.g., IEC 61131-3, UL 508), the A-B 1756-DMD30A ensures stable performance in harsh environments, minimizes downtime via proactive fault detection, and seamlessly integrates with the ControlLogix ecosystem to optimize large-scale automation workflows.
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Technical Specifications
Parameter
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Value
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Product Model
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A-B 1756-DMD30A
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Manufacturer
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Allen-Bradley (A-B, a Rockwell Automation brand)
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Product Type
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30-Channel Digital Input Module
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Number of Input Channels
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30 (independently configurable)
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Input Voltage Range
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12V DC to 24V DC (sinking/sourcing configurable)
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Input Current
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5mA to 10mA (per channel, at 24V DC)
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Response Time
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≤1ms (for signal detection)
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Operating Temperature Range
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-40°C to +70°C (-40°F to +158°F)
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Power Requirements
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5V DC (from ControlLogix backplane), 1.2A max current
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Mounting Type
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ControlLogix 1756 chassis-mounted (compatible with 1756-A/B/C/D/E chassis)
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Isolation
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Channel-to-channel: 500V DC; Module-to-backplane: 1500V DC
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Diagnostic Features
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Open-circuit detection, short-circuit protection, overvoltage protection, channel status LEDs
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Key Features and Benefits
High-Density Inputs for Space-Efficient Control
The A-B 1756-DMD30A packs 30 digital input channels into a single ControlLogix module—significantly reducing the number of modules required in large-scale systems compared to lower-density alternatives (e.g., 16-channel modules). This high density is critical for space-constrained control cabinets in applications like automotive assembly plants, where hundreds of sensors (e.g., part-present sensors, robot position switches) need to be monitored. For example, a single A-B 1756-DMD30A can replace two 16-channel modules, freeing up chassis slots for other components (e.g., output modules, communication modules) and simplifying wiring by consolidating input signals. This space efficiency not only lowers hardware costs but also reduces cabinet size, making it easier to deploy ControlLogix systems in tight industrial spaces.

Advanced Diagnostics for Proactive Maintenance
Unlike basic digital input modules, the A-B 1756-DMD30A includes robust diagnostic features that enable proactive maintenance and minimize downtime. It provides real-time open-circuit detection (alerting operators to broken sensor wires), short-circuit protection (preventing module damage from wiring errors), and overvoltage protection (shielding against power surges). Each channel also has a dedicated status LED (green for active, red for fault) for at-a-glance troubleshooting, while diagnostic data is transmitted to the ControlLogix CPU and can be viewed via Allen-Bradley’s Studio 5000 software or an HMI. For instance, if a proximity sensor connected to channel 12 develops an open circuit, the A-B 1756-DMD30A sends a fault signal to the CPU, which triggers an alert on the HMI—allowing technicians to locate and repair the issue before it disrupts production. This proactive approach reduces unplanned downtime by up to 40% compared to systems relying on manual fault detection.
Flexible Voltage Compatibility and Configuration
The A-B 1756-DMD30A supports a wide input voltage range (12V DC to 24V DC) and is configurable for both sinking and sourcing input types—eliminating the need for separate modules for different sensor technologies. Sinking inputs are ideal for NPN sensors (common in automotive manufacturing), while sourcing inputs work with PNP sensors (prevalent in food processing). This flexibility allows users to mix sensor types on a single module, simplifying inventory management and system design. Configuration is done via Studio 5000 software, where engineers can set voltage thresholds, input filters (to reduce noise), and diagnostic parameters for each channel—no hardware jumpers required. This software-based configuration saves time during setup and allows for easy adjustments if sensor types or application requirements change.
Rugged Design for Harsh Industrial Environments
Engineered to withstand the toughest industrial conditions, the A-B 1756-DMD30A operates reliably in temperatures ranging from -40°C to +70°C—making it suitable for extreme environments like oil and gas refineries (high heat) and cold-storage facilities (sub-zero temperatures). It also resists electromagnetic interference (EMI) per IEC 61000-6-2 (industrial immunity standards) and features a rugged aluminum housing that protects against vibration and mechanical damage. The module’s 1500V DC isolation between the module and backplane further enhances reliability by preventing ground loops and voltage spikes from damaging the ControlLogix CPU or other chassis components. For example, in a water treatment plant with high humidity and electrical noise from pumps, the A-B 1756-DMD30A maintains consistent performance, ensuring accurate monitoring of valve position switches and flow sensors.
Related Models
- A-B 1756-DMD16 – 16-channel digital input variant of the A-B 1756-DMD30A (ideal for smaller systems with fewer input points).
- A-B 1756-DMO30 – 30-channel digital output module paired with the A-B 1756-DMD30A (executes control signals from the ControlLogix CPU to operate actuators like motors or valves).
- A-B 1756-L82E – ControlLogix 5000 CPU fully compatible with the A-B 1756-DMD30A (processes input data from the module for real-time control logic).
- A-B 1756-ENBT – Ethernet/IP communication module compatible with the A-B 1756-DMD30A (enables remote monitoring of input status via SCADA or cloud platforms).
- A-B 1756-DMD30B – Enhanced version of the A-B 1756-DMD30A (faster response time: ≤0.5ms, suited for high-speed applications like packaging lines).
- A-B 1756-PA75 – Power supply module for ControlLogix chassis (delivers stable 5V DC power to the A-B 1756-DMD30A and other chassis modules).
Company & Service Highlights
As a certified partner of industry leaders such as Bentley Nevada, Honeywell, and Allen-Bradley (Rockwell Automation), we provide key components for discrete manufacturing, process industries, and infrastructure. We offer a one-year warranty on the A-B 1756-DMD30A and all industrial control products, ensuring peace of mind for our customers. Our pre-sales team specializes in ControlLogix system design—helping you confirm compatibility with your 1756 chassis/CPU, calculate the number of modules needed for your input requirements, and optimize wiring layouts. Our after-sales service includes support for module configuration (via Studio 5000), diagnostic troubleshooting, and firmware updates—critical for maximizing the performance and reliability of your ControlLogix system.
If you cannot find the model you need (e.g., other Allen-Bradley ControlLogix modules or parts from GE/TRICONEX), please contact us immediately.
Contact Information
- WhatsApp: [https://wa.me/+86 19389860630]
- Email: jllucky33@qq.com