Allen-Bradley 1794-IM16 Flex I/O Digital Input Module

Product Overview

The 1794-IM16 comes from Allen-Bradley as a high-voltage AC input module. First, this device belongs to the popular Flex I/O series. Specifically, it provides 16 non-isolated digital inputs for industrial applications. Therefore, the 1794-IM16 works well for direct connection to 240V AC field devices. You can use this module with a central controller via the Flex I/O backplane. Consequently, it expands your system's AC input capacity without external signal conditioning. For example, you can connect up to 16 limit switches or proximity sensors directly to this module.

Technical Specifications (Voltage Ratings)

The 1794-IM16 operates at standard industrial AC voltage levels. Specifically, the nominal on-state voltage sits at 240V AC. Meanwhile, the input voltage range spans from 159V AC to 264V AC. This range accommodates typical line voltage fluctuations in industrial facilities. As a result, the 1794-IM16 performs reliably even with unstable power sources. In comparison, many competitor modules require tighter voltage tolerances. Moreover, this module supports 50 or 60 Hz frequency automatically. Thus, you can use it anywhere in the world without adjustments.

Technical Specifications (Current and Impedance)

Current handling on the 1794-IM16 is optimized for AC input applications. First, the module draws 11 mA of input current at 240V AC. This low current minimizes heat generation in your field devices. Meanwhile, the nominal input impedance measures 22.2 kΩ. This high impedance value prevents excessive loading on your sensor power supplies. Consequently, the 1794-IM16 works with a wide range of AC field devices. In addition, the Flexbus current draw is only 32 mA at 5V DC. Therefore, this module places very low demand on your backplane power supply.

Technical Specifications (Power and Thermal Data)

The 1794-IM16 maintains efficient power usage despite its high voltage rating. Specifically, the maximum power dissipation reaches 6 watts at 264V AC. Thus, it stays cool during continuous operation. Moreover, the thermal dissipation measures 20.47 BTU/hr at 264V AC. For instance, you can install multiple modules without overheating your enclosure. As a result, the 1794-IM16 suits high-density Flex I/O racks. The inputs are designed as non-isolated types for straightforward system integration.

Summary of Key Technical Parameters

• Number of Inputs: 16 non-isolated digital inputs

• Nominal On-State Voltage: 240V AC

• Input Voltage Range: 159 to 264V AC

• Nominal Input Current: 11 mA at 240V AC

• Nominal Input Impedance: 22.2 kΩ

• Flexbus Current: 32 mA at 5V DC

• Maximum Power Dissipation: 6 W at 264V AC

• Thermal Dissipation: 20.47 BTU/hr at 264V AC

• Input Type: AC voltage sensing

• Isolation: Non-isolated between inputs

Environmental and Mechanical Data

The 1794-IM16 shares the same rugged design as other Flex I/O modules. First, it operates in temperatures from 0 to 55 °C (32 to 131 °F) . Meanwhile, storage temperatures range from -40 to 85 °C (-40 to 185 °F). The module withstands vibration of 5 g at 10-500 Hz. Additionally, it handles operating shock of 30 g peak acceleration. Therefore, the 1794-IM16 suits harsh factory environments. The module measures approximately 94 x 94 x 91 mm (3.7 x 3.7 x 3.6 inches) . For reference, it weighs only about 141 grams (4.97 oz) . As a result, installation requires very little panel space. This compact design delivers substantial functionality for your Flex I/O system.

Input Response and Filtering

The 1794-IM16 processes AC input signals with built-in filtering. First, the module rectifies the AC voltage internally. Then, it applies a filter to convert the signal to a DC logic level. Consequently, the 1794-IM16 rejects electrical noise commonly found on AC lines. The input filter time is fixed but suitable for most industrial applications. For example, you can use this module with AC proximity sensors, push buttons, and selector switches. Thus, it provides reliable input detection even with slow-changing AC signals.

Installation Guidelines

Mount the 1794-IM16 on a standard DIN rail or using screws. First, attach the module to a compatible terminal base unit. For example, suitable bases include the 1794-TB3 or 1794-TB3G series. Then, connect your AC field devices to the screw terminals. Connect individual inputs to their exact terminal numbers. Use stranded copper wire rated at 75 °C or higher. Recommended wire size ranges from 0.34 to 2.5 mm² (22 to 12 AWG). Tighten terminal screws to 0.8 Nm (7 lb-in). Accordingly, always disconnect power before wiring the 1794-IM16. Finally, ground the DIN rail properly to avoid noise issues. Keep AC input wiring separated from low-voltage DC signals.

Important installation notes include the following:

• Use a properly rated fuse for each input circuit.

• Do not exceed 264V AC on any input channel.

• Keep AC wiring away from sensitive analog signals.

• Verify the AC frequency matches your application (50/60 Hz).

• Use shielded cable in electrically noisy environments.

Packaging List

• 1794-IM16 digital input module (1 unit)

• Removable terminal block (attached to mating base)

• Product identification label

• Installation instructions sheet

Frequently Asked Questions (FAQ)

1. What voltage range does the 1794-IM16 support?
The 1794-IM16 accepts input voltages from 159V to 264V AC. Its nominal operating voltage is 240V AC at 50 or 60 Hz.

2. Can I use the 1794-IM16 with 120V AC signals?
No, the 1794-IM16 requires a minimum of 159V AC for reliable on-state detection. For 120V AC applications, please consider the 1794-IM8 module instead.

3. Is this module isolated from the backplane?
The 1794-IM16 provides non-isolated inputs. Specifically, all inputs share a common return path. Therefore, use caution when mixing voltages on different channels.

4. What terminal bases work with this module?
The 1794-IM16 works with standard Flex I/O terminal bases. For example, the 1794-TB3 and 1794-TB3G are compatible options.

5. How do I know which input is active?
Each channel on the 1794-IM16 has a status indicator LED. The LED illuminates when the AC input voltage exceeds the threshold. Thus, you get clear visual feedback for every channel.