Allen-Bradley 1746-OB16 SLC500 DC Output Module

1746-OB16 Allen-Bradley 16-Channel DC Output Module

Product Introduction

The Allen-Bradley 1746-OB16 provides a high-density DC output solution for the SLC500 control system. This module features sixteen independent output channels arranged in a single group with a common return. It operates at a nominal voltage of 24 VDC, yet it accepts a wide input range from 10 to 50 VDC, offering exceptional flexibility for various DC power supplies. Each output delivers 1.5 A continuously at 30 °C, making the 1746-OB16 a powerful choice for driving DC loads. Its fast switching speeds and low leakage current ensure precise and reliable control in demanding automation applications.

Technical Specifications

Output Capacity and Current Ratings
The 1746-OB16 offers sixteen DC outputs with a single common connection. Each point supports a continuous current of 1.5 A at 30 °C (86 °F), derating to 1.0 A at 55 °C (131 °F). The total module current reaches 6.4 A across the full 0-60 °C temperature range. Each output handles a surge current of 2.0 A for 10 milliseconds, providing tolerance for inrush loads. The on-state voltage drop is exceptionally low at 0.25 V at 0.5 A, minimizing power loss and heat generation. Total heat dissipation for the module measures 7.6 W.

Timing and Switching Performance
This module delivers extremely fast switching response. The ON signal delay is just 1.0 ms, while the OFF signal delay is an impressive 0.1 ms. This rapid switching makes the 1746-OB16 ideal for high-speed applications like positioning systems or high-frequency valve actuation. The OFF-state leakage current stays at a minimal 1 mA, preventing unintended activation of sensitive loads. The minimum load current requirement is just 1.0 mA per channel.

Power Consumption
The 1746-OB16 draws only 135 mA from the 5 VDC backplane. This low power consumption allows you to install multiple modules without overloading the system power supply. The module does not draw current from the 24 VDC backplane supply.

Isolation and Protection
This output module includes optical isolation between the backplane and the output circuits. This protects the processor from electrical noise and transient voltages on the field wiring. Furthermore, the 1746-OB16 features internal short-circuit protection, safeguarding the module from wiring faults. The outputs are also protected against reverse voltage and over-temperature conditions.

Mechanical and Environmental Parameters

Physical Design
The 1746-OB16 occupies a single slot in the SLC500 chassis. Its compact size allows efficient use of rack space. The removable terminal block simplifies wiring and maintenance. You can replace the module without disconnecting field wires, significantly reducing downtime during troubleshooting or upgrades.

Temperature and Humidity
This module operates reliably from 0 °C to 60 °C (32 °F to 140 °F). It also tolerates relative humidity between 5% and 95%, non-condensing. These environmental ratings ensure consistent performance across diverse factory floor conditions.

Shock and Vibration
The 1746-OB16 withstands operational shock of 30G and vibration of 5G at 10-500 Hz. These rugged specifications make it suitable for demanding environments with heavy machinery or conveyor systems.

Installation and Integration Guide

Mounting Procedure
First, verify your chassis power supply can accommodate the additional 135 mA backplane load. Then, select an available slot in the SLC500 rack. Insert the 1746-OB16 carefully, aligning it with the backplane connector. Press firmly until the module seats completely. Finally, secure it with the retaining screws to prevent loosening from vibration.

Wiring Recommendations
Connect your DC loads to the appropriate terminals on the removable connector. All outputs share a common return terminal (COM). Ensure your power supply stays within the 10-50 VDC range. Use properly sized conductors for the expected load currents. For inductive loads like relays or solenoids, install a flyback diode across the load to suppress voltage spikes and protect the output transistor.

Programming and Addressing
The 1746-OB16 occupies 16 bits of the output image table in your SLC500 processor. Each channel maps to a specific bit address. You control outputs using standard ladder logic instructions like OTE (Output Energize) or OTU (Output Unlatch). The module's front panel features LED indicators for each channel. These provide immediate visual feedback on output status, simplifying field troubleshooting.

Packaging List

• Allen-Bradley 1746-OB16 Discrete DC Output Module (1 unit)

• Removable terminal block connector (1 unit, 20 positions)

• Installation instruction sheet

Note: Cables and programming software are not included.

Shipping Information

All orders ship via FedEx, UPS, or DHL with tracking numbers provided. Please ensure your shipping address and contact details are correct for prompt delivery.

Frequently Asked Questions

1. What is the difference between the 1746-OB16 and the 1746-OW16?
The 1746-OB16 is a DC output module with transistor outputs, offering fast switching speeds (0.1 ms OFF delay). The 1746-OW16 is a relay output module, which supports both AC and DC loads but switches much slower. Choose the 1746-OB16 for high-speed DC applications.

2. Can I use this module with a 48 VDC power supply?
Yes, the 1746-OB16 accepts an operating voltage range of 10 to 50 VDC. This includes 48 VDC systems, provided the supply stays within this range. However, verify your load current derating at higher voltages.

3. Does the 1746-OB16 provide short-circuit protection?
Yes, this module includes internal short-circuit protection on each output. When a short occurs, the affected channel shuts down to prevent damage. The output automatically recovers once the fault condition clears.

4. How do I connect inductive loads to this module?
For inductive DC loads such as relays or solenoids, install a flyback diode across the load terminals. Connect the diode's cathode to the positive supply and the anode to the return. This suppresses voltage spikes and protects the output transistor.

5. Is the 1746-OB16 compatible with 5 VDC logic signals?
No, the 1746-OB16 operates at 10-50 VDC output levels. It is not designed for 5 VDC logic signals. For 5 VDC outputs, consider the 1746-OB5 or 1746-OB6 modules instead.