Product Overview
The Allen-Bradley 1756-OB32 is a high-density ControlLogix DC output module designed to drive discrete output devices such as pilot lamps, relays, contactors, solenoids, and annunciators. It provides reliable ON/OFF control and is ideal for applications where space is limited, as it occupies a single slot in a local or remote ControlLogix chassis.
This module operates at a voltage category of 12/24V DC with an operating voltage range of 10-31.2V DC. It features 32 output points arranged in two groups of eight channels, each with individual configuration and output forcing capabilities. The front panel includes 32 LED indicators for real-time channel status monitoring, simplifying troubleshooting.
Technical Specifications
Key performance parameters for the Allen-Bradley 1756-OB32 ensure dependable operation in demanding industrial environments:
| Parameter |
Value |
| Series |
ControlLogix |
| Outputs |
32-Point |
| Module Type |
DC Output Module |
| Voltage |
12-24 Volts DC Source |
| Operating Voltage Range |
10-31.2 Volts DC |
| Output Delay Time, OFF to ON |
60 µs nom / 1 ms max |
| Output Delay Time, ON to OFF |
200 µs nom / 1 ms max |
| Current per Point |
0.5 A @ 50 °C, 0.35 A @ 60 °C (linear derating) |
| Current per Module |
16 A @ 50 °C, 10 A @ 60 °C (linear derating) |
| Power Dissipation (Max) |
4.8 Watts @ 60 °C |
| Backplane Current at 5 Volts |
300 milliamps |
| Isolation Voltage |
50 Volts Continuous |
These specifications allow the 1756-OB32 to handle moderate current loads while maintaining fast response times, making it suitable for high-speed switching applications.
Industry Applications
Thanks to its compact design and high output density, the Allen-Bradley 1756-OB32 is widely used in manufacturing, material handling, and process control systems. Typical applications include:
- Controlling motor contactors and starters in conveyor systems.
- Driving indicator lamps and panel annunciators in control cabinets.
- Actuating solenoids and valves in automated assembly lines.
With 32 outputs in a single slot, this module maximizes I/O capacity without expanding the chassis, reducing both footprint and cost.
Installation & Setup
Mount the Allen-Bradley 1756-OB32 directly into any ControlLogix local or remote chassis. Ensure the chassis is properly grounded and the power supply is connected before installing the module. The module requires a Removable Terminal Block (RTB) for field wiring; use either the 1756-TBCH (cage clamp) or 1756-TBS6H (spring clamp) RTB. For fuse protection, a 5x20mm 800 mA fuse (Littelfuse p/n SP001.1003 or Schurter p/n 216.800) is recommended. After installation, verify that the module is securely seated and the RTB is locked in place.
Maintenance & Reliability
Routine maintenance of the 1756-OB32 is minimal. Periodically inspect the RTB connections for tightness and check the LED indicators for any anomalies. The module operates within a temperature range of 0 to 60 °C, so ensure adequate ventilation in the enclosure. The use of high-quality fuses and proper wiring practices will enhance long-term reliability and reduce downtime.
Compatibility & Integration
The Allen-Bradley 1756-OB32 is compatible with all ControlLogix processors, including the latest versions. It supports multiple communication formats, including scheduled output data, output data, rack optimization, listen-only rack optimization, and listen-only output data. You can configure per-point fault and program mode states (Hold Last State, On, or Off) to suit your application needs.
Buying Guide
When purchasing the Allen-Bradley 1756-OB32, verify the exact part number and ensure you have the correct RTB (1756-TBCH or 1756-TBS6H) for your wiring preferences. The module is a sourcing output type, so it is not suitable for sinking applications. For genuine automation spares and reliable service, consider PLC Source PRO as your trusted supplier.