Overview
The Allen-Bradley 1746-OB16 is a discrete DC output module designed for SLC500 programmable logic controllers. This 16-point output module provides current-sourcing 24V DC outputs for controlling external devices such as solenoids, relays, and indicator lights. Series D units deliver reliable switching performance with integrated electronic protection against short circuits and overload conditions, making this module an essential component in industrial automation systems requiring discrete output control.
Key Features
- 16 DC Output Points — All outputs grouped for streamlined control and simplified programming.
- 24V DC Nominal Output with operating range of 10–50V DC, providing flexibility in various industrial applications.
- Fast Signal Response — 0.1ms ON delay and 1.0ms OFF delay on maximum resistive load, ensuring responsive system performance.
- Thermal Overload Protection — Module limits current on overloaded channels within milliseconds once temperature threshold is reached, with automatic channel reset capability.
- Low Backplane Current Draw — 0.280A at 5V DC and 0A at 24V DC, minimizing power consumption and heat generation.
- Compact Single-Slot Design — Fits any open slot in 1746 I/O chassis (except leftmost processor slot).
Technical Specifications
- Output Voltage (Nominal): 24V DC
- Output Voltage Range: 10V to 50V DC
- Output Points: 16 grouped
- Output Current per Point: 1.5A @ 30°C, 1.0A @ 60°C
- Continuous Module Current: 8.0A @ 30°C, 4.0A @ 60°C
- Signal ON Delay: 0.1ms (maximum resistive load)
- Signal OFF Delay: 1.0ms (maximum resistive load)
- OFF-State Leakage Current: 1mA maximum
- ON-State Voltage Drop: 1.2V @ 0.50A
- Minimum Load per Point: 1mA
- Backplane Current Draw: 0.280A @ 5V DC, 0.0A @ 24V DC
- Heat Dissipation: 0.388 watts per point, 7.6 watts total
- Surge Current: 3.0A for 10ms per point
- Protection: Electronic overload and short-circuit protection (thermal cut-out)
- Certifications: Class I, Groups A, B, C, D; Division 2
Typical Applications
The 1746-OB16 features sixteen 24VDC output channels used to energize electrical devices for implementing manual and automatic control of processes or machines. Common uses include:
- Discrete solenoid and valve control in manufacturing systems
- Indicator light and alarm signal actuation
- Motor starter and contactor output circuits
- Process equipment enable/disable logic
- Conveyor and material handling system control
Compatibility & Replacements
Compatible With
- SLC500 fixed and modular processors
- 1746 I/O chassis (open slots only)
- RSLogix 500 programming software
- Allen-Bradley automation networks
- External 24V DC load devices and relays
Replaces / Drop-In Replacement For
- Previous generation 1746-OB16 modules (earlier series)
- Direct fit for 1746 chassis containing legacy 1746-OB16 configurations
Works With
- RSLogix 500 development environment
- SLC500 instruction set and output commands (OTE, OUT)
- 1746-A2 power supply units
- Standard 24V DC external load circuits
- Thermal and electronic overload relay monitoring
