Description

The Allen-Bradley 1756-OB32 is a high-density ControlLogix digital output module designed for industrial automation environments. It provides 32 sourcing DC outputs, organized into two groups of 16 points each. This module is engineered for reliable operation within a voltage range of 10 to 31.2V DC, making it suitable for 12V or 24V DC control applications. It occupies a single slot in a standard ControlLogix chassis and integrates seamlessly with the backplane for high-speed data exchange and status reporting.

Features

• 32-point sourcing DC digital outputs
• Two isolated groups of 16 points
• Fast switching response times (1 ms max turn-on, 2 ms max turn-off)
• Electronic current limiting and short-circuit protection per channel
• Reverse polarity and thermal protection
• Configurable fault and program states via software
• Compatible with 1756-TBCH, 1756-TBS6H, and 1756-TBNH removable terminal blocks (RTB)

Applications

• Water/Wastewater: Control of chemical dosing pumps and effluent valve positioning.
• Oil, Gas, and Petrochemical: Management of pressure loops and precision burner gas-feed systems.
• Food and Beverage: Temperature regulation for mixing and cooking processes via PID logic.
• Power Generation: Integration of cooling tower fan systems and steam governor actuators.

Technical Specifications

Installation Guidelines

• Power Down: Always disconnect all chassis and field-side power before inserting or removing the module to prevent electrical arcing or damage to the backplane.
• Mounting: Align the module horizontally with the top and bottom card guides of the intended ControlLogix chassis slot. Push firmly until the chassis latches click to ensure a secure connection.
• Keying: Utilize the mechanical keying system on the Removable Terminal Block (RTB) to prevent the insertion of an incorrectly configured RTB into this slot.
• Wiring: Ensure proper grounding and use shielded cabling where required to minimize EMI. Verify that external field power is correctly fused according to load requirements.

FAQs

What is the operating voltage?

The module operates within a range of 10 to 31.2V DC, with nominal operation at 12V or 24V DC.

Which terminal blocks are compatible?

The module requires a 36-pin removable terminal block (RTB), such as the 1756-TBCH (cage clamp) or 1756-TBS6H (spring clamp). These are sold separately.

Why are half of my outputs not working?

This is often caused by a blown internal 10A fuse. Each 16-point group is protected by an internal fuse; a short circuit in the field wiring will cause this fuse to open.