1746-NI4 | Allen-Bradley SLC 500 Analog Input Module Supplier

What Is the 1746-NI4 Analog Input Module?

When your SLC 500 control system requires accurate analog signal acquisition from field devices, the 1746-NI4 provides a reliable solution. This Allen-Bradley module offers four non-isolated differential input channels that accept either voltage or current signals, making it a versatile choice for monitoring and control applications. As part of the SLC 500 series from Rockwell Automation, this analog I/O module occupies a single slot in the chassis and works with both fixed and modular hardware configurations.

The 1746-NI4 features user-selectable input ranges of -20 to +20 mA or -10 to +10V dc, allowing you to connect a wide variety of sensors and transmitters. Its 16-bit resolution ensures fine granularity in measurement, which is critical for processes that demand high accuracy. With a bandwidth of 10 Hertz, the module filters out high-frequency noise, delivering stable readings for industrial environments.

Key Features & Technical Specs

• Input channels: Four differential, non-isolated channels, individually selectable for voltage or current.
• Input signal categories: -20 to +20 mA or -10 to +10V dc.
• Resolution: 16 bits, with converter resolution also 16 bit.
• Backplane current draw: 25 milliamps at 5 Volts; 85 milliamps at 24 Volts DC.
• Update time: 512 microseconds for fast data refresh.
• Step response: 60 milliseconds, ensuring timely reaction to input changes.
• Conversion type: Delta–Sigma Modulation for accurate analog-to-digital conversion.
• Input coding: Current input coding from -16,384 to +16,384; voltage input coding from -32,768 to +32,767.
• Repeatability: ±1 LSB for consistent measurements.
• Non-linearity: 0.01% for high linearity across the range.
• Chassis location: Any I/O module slot except slot 0.
• Cable lengths: Available in 0.5, 1, 2.5, or 5.0 meters.

A distinctive spec is the 16-bit resolution paired with Delta–Sigma Modulation, which minimizes noise and quantization error. In real-world terms, this means the 1746-NI4 can detect minute changes in process variables, such as a 0.1% variation in a pressure transmitter’s output, enabling tighter control loops and reduced product waste.

Industry Applications & Use Cases

The 1746-NI4 is suited for applications that require monitoring of analog signals from sensors like pressure transmitters, temperature probes, and flow meters. For example, in a water treatment facility, operators can use this module to measure flow rates from multiple points, ensuring consistent chemical dosing. Similarly, in packaging lines, the module can monitor position feedback from linear transducers, improving machine synchronization. Its combination of 120 Volts AC I/O capability makes it adaptable to mixed-voltage environments common in industrial settings.

Installation & Setup

Installing the 1746-NI4 is straightforward: insert it into any available I/O slot (except slot 0) of the SLC 500 chassis. The module includes a removable terminal block for connecting field wiring. Before powering up, verify that the DIP switches on the circuit board are set to match your input type—voltage or current. Use the specified cable lengths (0.5, 1, 2.5, or 5.0 meters) to maintain signal integrity. Avoid connecting a voltage source to a channel configured for current input, as this may cause incorrect operation or damage.

Maintenance & Reliability

To ensure long-term reliability, periodically inspect the module’s LED indicators for channel status and overall health. The built-in diagnostics can be accessed via the controller’s diagnostic interrupt, speeding up troubleshooting. Keep the chassis environment within specified temperature and humidity ranges to prevent drift. Regular inspection per the manufacturer’s manual helps maintain accuracy over time.

Compatibility & Integration

The 1746-NI4 integrates seamlessly with SLC 500 fixed or modular controllers. It communicates over the backplane, requiring 25 milliamps at 5 Volts and 85 milliamps at 24 Volts DC. The module works with any I/O slot except slot 0, which is reserved for the processor. For scaling and data processing, the module outputs raw counts that can be converted using the scaling algorithm in your control program.

Common Questions About the 1746-NI4

Q: What is the resolution of the 1746-NI4?

A: The module has a 16-bit resolution for both its converter and overall measurement.

Q: Can the 1746-NI4 accept both voltage and current inputs on the same channel?

A: No, each channel must be configured for either voltage or current via DIP switches. You cannot use both on the same channel simultaneously.

Q: What is the update time of the 1746-NI4?

A: The update time is 512 microseconds, providing fast data refresh for control loops.

Q: Is the 1746-NI4 isolated from the backplane?

A: The module features non-isolated differential inputs, meaning the channels share a common reference with the backplane.

Q: What cable lengths are supported for the 1746-NI4?

A: Standard cable lengths are 0.5, 1, 2.5, or 5.0 meters.

Product Support & Availability

The 1746-NI4 is in stock and ready to ship from Petro Auto Tech. As a trusted supplier of industrial automation parts, Petro Auto Tech offers competitive pricing and fast delivery. Please verify current lifecycle status and availability with Petro Auto Tech before ordering.

Customer Case Scenario (Illustration)

Consider a chemical plant that monitors pH levels across four tanks using analog pH transmitters. By installing the 1746-NI4 in their SLC 500 system, engineers can read all four signals with 16-bit resolution, enabling precise acid/base dosing adjustments. The module’s fast 512-microsecond update time ensures the control loop responds quickly to pH changes, preventing batch quality issues.