Allen-Bradley 1791-NDV Analog Block I/O Module with 4 Inputs and 2 Outputs

Product Introduction

When your control system demands precise analog signal handling in a compact form factor, the Allen-Bradley 1791-NDV delivers. This 24 Volts DC analog block I/O module from the 1791 Block I/O series integrates 4 input channels and 2 voltage output channels into a single, rugged unit. Designed for distributed I/O applications, the 1791-NDV simplifies wiring and reduces panel space while maintaining the reliability expected from Allen-Bradley.

Technical Specifications Breakdown

The 1791-NDV module offers a 14-bit full-scale resolution, ensuring accurate conversion of analog signals. Each input channel features an impedance of 10 Megohm Volts, minimizing signal loading, while the input bandwidth is rated at 5 Hertz, suitable for slow-changing process signals. The module provides an update rate of 108 milliseconds per channel, balancing responsiveness with noise rejection.

For output channels, the 1791-NDV provides voltage outputs with an output impedance of less than 1 Ohm, enabling stable drive to connected loads. Indefinite short circuit protection safeguards the outputs against accidental faults. The absolute accuracy is 0.1% at 25 degrees Celsius, with linearity rated at 0.05% at 25 degrees Celsius, ensuring reliable measurement over the operating range.

The module operates from an external power supply of 19.2 to 30 Volts DC, drawing up to 600 milliamps. Power dissipation is 11.52 Watts, with maximum thermal dissipation of 39.28 BTU per hour. Overvoltage protection is rated at 140 Volts AC input and output, adding robustness in industrial environments.

Industry Applications

The 1791-NDV is ideal for applications requiring mixed analog I/O in a single block. In process control, it can monitor four analog sensors (e.g., pressure or temperature transmitters) while simultaneously driving two analog actuators (e.g., valve positioners or variable speed drives). The 14-bit resolution and 0.1% accuracy support precise regulation in chemical processing, water treatment, and packaging lines.

In material handling systems, the module's compact size (2.7 x 3.85 x 6.95 inches) allows mounting close to sensors and actuators, reducing cable runs and signal degradation. The 108-millisecond update rate is well matched to conveyor monitoring and discrete manufacturing processes where fast response is not critical but reliability is paramount.

Installation & Setup Guidance

Mount the 1791-NDV on a DIN rail or panel using the integral mounting slots. Ensure the ambient operating temperature stays between 0 and 60 degrees Celsius, with relative humidity between 5 and 95% non-condensing. Connect the external power supply (19.2 to 30 Volts DC) to the designated terminals, observing polarity. The input shunt resistor is 249 Ohms rated at 0.25 Watts — never exceed this rating to avoid damage. Wire analog inputs and outputs using shielded twisted-pair cable, keeping signal wiring separate from power cables to minimize noise.

Maintenance & Reliability

The 1791-NDV requires minimal routine maintenance. Periodically inspect the module for dust accumulation, loose connections, or signs of overheating. Verify that the ambient temperature remains within the 0 to 60 degrees Celsius range and that the relative humidity stays below 95% non-condensing. The indefinite short circuit protection on outputs reduces the risk of damage from wiring faults. For long-term reliability, ensure the power supply voltage stays within the 19.2 to 30 Volts DC range and that the load current does not exceed the module's rating.

Selection Guide & Purchasing Advice

Before purchasing the 1791-NDV, verify that your system requires a 24V DC analog block I/O module with 4 inputs and 2 voltage outputs. Confirm that the input signal types (voltage or current) match the module's 10 Megohm input impedance and 5 Hertz bandwidth. For applications needing faster update rates or higher resolution, consider other modules in the 1791 family. BluePLC Industrial stocks the 1791-NDV and can provide current availability and lifecycle status. For complete technical specifications, please contact BluePLC Industrial.