Product Overview
The Allen-Bradley 1791-NDV is a compact analog block I/O module engineered for distributed control applications. With 4 input channels and 2 voltage output channels, this unit consolidates signal acquisition and actuation into a single, space-saving enclosure. Designed for PLC systems, the 1791-NDV operates on 24 VDC and delivers reliable performance in demanding industrial environments.
Key Technical Specifications
| Parameter |
Value |
| Manufacturer |
Allen-Bradley |
| Product Line |
1791 Block I/O |
| Part Number |
1791-NDV |
| Input Channels |
4 |
| Output Channels |
2 |
| Update Rate |
108 ms per channel |
| Input Impedance |
10 MΩ (voltage), 250 Ω (current) |
| Absolute Accuracy |
0.1% at 25°C |
| Linearity |
0.05% at 25°C |
| Output Impedance |
< 1 Ω |
| Resolution |
14 bits full scale |
| Input Bandwidth |
5 Hz |
| Overvoltage Protection |
140 VAC (input/output) |
| External Power Voltage |
19.2 – 30 VDC |
| Current Rating |
600 mA |
| Power Dissipation |
11.52 W |
| Thermal Dissipation |
39.28 BTU/hr |
| Weight |
1.19 lbs (0.54 kg) |
| Dimensions (W x D x H) |
2.7 x 3.85 x 6.95 in |
| Operating Temperature |
0 to 60 °C |
| Storage Temperature |
-40 to 85 °C |
| Relative Humidity |
5 to 95% non-condensing |
Performance and Reliability
The 1791-NDV delivers an update rate of 108 ms per channel, making it suitable for processes that require moderate response times. Its 14-bit resolution ensures precise signal conversion, while the absolute accuracy of 0.1% at 25°C guarantees dependable measurement. The module features overvoltage protection up to 140 VAC, safeguarding connected equipment from voltage spikes. With an output impedance of less than 1 Ω and indefinite short-circuit protection, the 1791-NDV ensures stable output driving and robust fault tolerance.
Applications and Use Cases
This Allen-Bradley 1791-NDV module is ideal for applications such as:
- Process control systems requiring analog signal conditioning
- Machine automation where compact I/O blocks are needed
- Remote monitoring stations that demand reliable data acquisition
- Legacy system upgrades where space is limited
Its 4 inputs and 2 outputs allow you to handle sensor readings and actuator commands from a single unit, reducing wiring complexity and panel space.
Installation and Setup
Mount the Allen-Bradley 1791-NDV on a standard DIN rail or panel using the integrated mounting slots. Ensure the supply voltage is within 19.2 to 30 VDC and that the current draw does not exceed 600 mA. Connect input signals to the designated terminals, observing polarity. For current inputs, use the internal 250 Ω shunt; for voltage inputs, the 10 MΩ impedance is already present. Verify that the ambient temperature stays within 0 to 60°C and that humidity remains non-condensing between 5% and 95%. Tighten all connections to the recommended torque and perform a continuity check before powering up.
Maintenance and Longevity
Periodically inspect the 1791-NDV for dust accumulation and ensure that ventilation is not obstructed. Check wiring for signs of wear or corrosion, especially in humid environments. The module's solid-state design has no moving parts, which minimizes mechanical failure. With proper environmental control, this Allen-Bradley module can provide years of trouble-free service, reducing downtime and replacement costs.
Selection Guide
When purchasing the 1791-NDV, verify that your control system accepts analog block I/O modules and that the input/output voltage ranges match your field devices. Confirm that the 24 VDC power supply can deliver the required 600 mA. This unit is a direct replacement for many older 1791 series modules. For guaranteed quality and reliable sourcing, choose PLC Source PRO as your trusted supplier for industrial automation spares.