Allen-Bradley 1790D-N0C2 - Dual-Channel Precision Analog Current Output Module

Deliver precise control signals with the Allen-Bradley 1790D-N0C2. This specialized ArmorBlock module provides two high-accuracy 0-20 mA analog current outputs on your DeviceNet network. With 12-bit resolution and excellent overall accuracy, it's engineered to drive control valves, I/P converters, speed references, and other critical analog actuators with reliability and precision in process and motion control applications.

Module Highlights

• High-Precision Control: Delivers a stable 0-20 mA signal with 0.2% full-scale accuracy and fine 12-bit resolution for precise actuator positioning.
• Fast & Stable Output: Features a rapid 2 ms conversion time per channel, ensuring quick response to control system commands for dynamic processes.
• Robust Industrial Design: Includes 1250V AC isolation between the field outputs and network logic, protecting against ground loops and electrical noise.
• Clear Dual-Color Diagnostics: Each channel has a dedicated red/green status LED that provides instant visual feedback on output state and communication health.

Complete Technical Specifications

Brand & Series: Allen-Bradley ArmorBlock (1790 Series)

Full Model Number: 1790D-N0C2

Module Type: 2-Channel Analog Current Output Module

Output Signal: 0 to 20 mA, single-ended, non-isolated between channels

Resolution: 12 bits (1 part in 4096, approx. 4.88 µA per bit)

Data Format: Binary, 0 to 4095 (0FFF hex)

Overall Accuracy: ±0.2% of full scale (0 to 55°C)

Conversion Time: 2 milliseconds per channel

Maximum Load Impedance: 600 Ω

Field Power Supply: 24V DC (+10%, 21.6V to 26.4V DC)

DeviceNet Logic Power: 24V DC (11V to 28.8V DC)

Electrical Isolation: 1250V AC RMS (Field outputs to logic, Type Test)

Status Indicators: 2 Bi-color (Red/Green) LEDs, one per channel

Wiring Connection: 37-pin D-shell connector

Expansion Capability: Can act as a base for up to 2 discrete expansion I/O modules.

Installation & Wiring Guide

Install the 1790D-N0C2 as a base module on your DeviceNet network. Provide a clean, stable 24V DC field power supply within the specified 21.6-26.4V range for optimal output accuracy. Connect your analog actuator (e.g., a control valve positioner) in a series loop: from the module's output terminal, through the actuator, and back to the module's common/return. Ensure the total loop resistance does not exceed 600 Ohms. Use shielded, twisted-pair cables for the analog signals and ground the shield at one end only.

Package & Warranty

What's Included: 1 x Allen-Bradley 1790D-N0C2 Analog Current Output Module.

Our Guarantee: This precision product is backed by a reliable 12-month warranty.

Fast Shipping Service

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Frequently Asked Questions (FAQ)

What does the status LED color indicate?

Typically, Green indicates normal operation with valid output data. Red can indicate a fault condition such as an open wire (broken loop), short circuit, or a configuration/data error from the network.

Can it output a 4-20 mA signal?

The hardware is designed for a 0-20 mA range. A 4-20 mA signal is achieved through software configuration in your DeviceNet master/scanner. You scale your data (e.g., 0-100%) to the output range 20% to 100% of 4095 counts.

Why is the field power supply range tighter (21.6-26.4V)?

Analog circuits require a more stable power supply for accurate current generation. The tighter voltage range ensures the output meets its specified accuracy of 0.2% across operating conditions.

What happens if the load exceeds 600 Ohms?

If the loop resistance is too high, the module cannot drive the required current to the full 20 mA. The output will saturate at a lower current, causing a loss of control range and potential system errors.

How is the output value scaled and sent?

Your DeviceNet master controller (PLC) sends a 16-bit integer value over the network. The module's internal 12-bit D/A converter uses the lower 12 bits of this value (0-4095) to generate the corresponding 0-20 mA output current.

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