Allen-Bradley 1746-IO8 SLC 500 I/O Module

Product Introduction

The 1746-IO8 module integrates digital inputs and relay outputs to solve space constraints in control cabinets. This combination I/O module belongs to the trusted Allen-Bradley SLC 500 family. It effectively reduces the number of modules needed for small to medium-sized applications.

This SLC 500 unit accommodates four 120V AC input points and four Normally Open (N.O.) relay outputs. The outputs are rated for 1.5A at 120V AC and 1.2A at 24V DC. The module fits into any slot except the first one, which is reserved for the processor. You can use it for various machine control and automation tasks.

Technical Specifications

The Allen‑Bradley 1746‑IO8 delivers reliable performance within a defined operating envelope.

Input and Output Configuration

This module features four dedicated input channels. It also has four relay contact outputs. The outputs share a common terminal for each group of four points. This compact design makes the 1746-IO8 ideal for applications requiring both sensing and actuation.

The input channels accept 85‑132V AC operating voltage. The signal delay times are 35‑45 milliseconds for both ON and OFF states. This predictable response suits many real‑time control loops.

Electrical Ratings and Power Consumption

The output contacts handle continuous currents of 1.5A at 120V AC and 1.2A at 24V DC. Meanwhile, the module draws only 0.03A at 5V DC and 0.025A at 24V DC from the backplane. This low current draw reduces the overall load on the system power supply.

Furthermore, the heat dissipation is minimal. Each input point dissipates 0.27W, and each output point dissipates 0.133W. The aggregate heat dissipation for the entire module is only 3W. Therefore, you can install this SLC 500 module without worrying about excessive temperature rise inside the cabinet.

Signal Timing and Response

The input and output signal delay is consistent at 35 ms for the ON state and 45 ms for the OFF state. This symmetrical timing allows for easier programming and troubleshooting. Additionally, the relay outputs are Normally Open, providing a fail‑safe state during power loss.

Environmental and Mechanical Specifications

The 1746-IO8 is built to withstand harsh industrial conditions while maintaining high reliability.

Operating and Storage Temperatures

The module operates within a temperature range of 0 to 60 °C (32 to 140 °F). Moreover, it can survive non‑operational storage from -40 to 85 °C (-40 to 185 °F). This broad range ensures the module remains functional even in regions with extreme seasonal changes.

Humidity tolerance is also impressive. It functions reliably at 5‑95% non‑condensing relative humidity. Therefore, you can deploy this module in environments with fluctuating moisture levels.

Shock and Vibration Resistance

The Allen‑Bradley 1746‑IO8 withstands operational shocks of 30G. Additionally, it tolerates operational vibration up to 2.5G at 57‑200Hz. This rugged construction makes it suitable for installations near heavy machinery or conveyor systems.

Agency Approvals and Standards

This module carries CE, CSA, and C‑UL certifications. It also meets NEMA standard ICS 2‑230 for noise immunity. These approvals give you confidence in its performance and safety.

Installation Guidelines

Installing the 1746-IO8 is straightforward if you follow a few key rules.

First, the module must be placed in any slot except slot 0, which the processor occupies. Second, ensure the chassis power is off before inserting or removing the module. Third, use proper grounding techniques to minimize electrical noise.

The module fits into any 1746 I/O chassis. For wiring, use copper conductors rated for at least 75 °C. Tighten terminal screws to the recommended torque of 0.56 N·m. Moreover, maintain a minimum clearance of 50 mm around the module for adequate airflow.

Finally, check the operating voltage before powering up. The SLC 500 module expects 85‑132V AC. Incorrect voltage may cause permanent damage. After installation, verify that all inputs and outputs respond correctly to test signals.

Packaging List

When you receive the 1746-IO8, the package includes the following items:

• One Allen-Bradley 1746-IO8 SLC 500 Digital I/O Combination Module

• One removable terminal block for field wiring

• One user manual (printed quick‑start guide)

• One mounting screw kit

Please note that the package does not include cables, power supplies, or configuration software. These items must be purchased separately.

Frequently Asked Questions

1. Can the 1746-IO8 be installed in slot 0 of the SLC 500 chassis?
No. Slot 0 is reserved exclusively for the SLC 500 processor. The 1746-IO8 must be placed in any slot from 1 to the maximum available slot number.

2. What is the maximum output current per point for this module?
For AC loads, the maximum current is 1.5A at 120V AC. For DC loads, it is 1.2A at 24V DC. Exceeding these ratings may damage the relay contacts.

3. Does the module support both AC and DC output loads?
Yes. The relay outputs are dry contacts. They support 5‑65V AC and 5‑125V DC loads at 47‑53Hz. This flexibility makes the 1746-IO8 versatile for different field devices.

4. What are the signal delay times for the input and output channels?
The ON‑state delay is 35 milliseconds, and the OFF‑state delay is 45 milliseconds. These delays are consistent across all four inputs and four outputs.

5. Which shipping carriers do you use for this module?
We ship all orders via FedEx, UPS, or DHL. Tracking numbers are provided within 24 hours of dispatch.