Allen-Bradley 1734-OB8S Safety Output Module

 

 

Product Overview

The Allen-Bradley 1734-OB8S is an 8-channel safety-rated digital output module from the POINT Guard I/O safety system.

It is used in safety automation circuits (SIL/PL systems) to control actuators such as:

• Safety contactors
• Solenoid valves
• Machine shutdown outputs
• Safety interlock devices

Key Specifications (confirmed)

• Brand: Allen-Bradley (Rockwell Automation)
• Series: POINT Guard I/O (1734)
• Model: 1734-OB8S
• Type: Safety digital output module
• Outputs: 8 channels
• Output Type: Sourcing (24V DC safety outputs)
• Voltage Range: 24 VDC nominal (19.2–28.8 VDC system range)
• Current: up to ~1A per channel, ~8A total module
• Reaction time: < 6.2 ms
• Short-circuit / cross-fault detection: Yes (electronic protection)
• Isolation: field vs system ~50V basic insulation
• Function: dual-channel / redundant safety control support

What “Safety Output” Means

Unlike normal output modules:

• Standard output = simple ON/OFF signal
• 1734-OB8S = safety-rated ON/OFF with diagnostics + redundancy

It continuously checks:

• Output short circuit
• Cross wiring faults
• Unexpected feedback states
• Module health status

If any abnormal condition is detected:

• It forces outputs to safe OFF state immediately

Key Features

• 8 safety-rated outputs in one module
• Designed for SIL/PL safety systems
• Continuous self-diagnostics
• Fault detection (short circuit, cross-wire, overload)
• Fast reaction time (<6.2 ms)
• Integrated into POINT I/O architecture
• Works with GuardLogix / safety controllers

Working Principle

The safety controller sends redundant signals → module validates → output energizes:

1. Safety PLC sends dual-channel command
2. Module performs internal checks (pulse testing)
3. If safe conditions are met → outputs energize
4. If mismatch or fault → outputs shut down immediately

This ensures fail-safe operation (default to OFF).

Advantages

• High safety integrity (industrial safety rated)
• Detects wiring faults automatically
• Fast response for emergency stop systems
• Suitable for machine safety circuits
• Modular POINT I/O design (easy expansion)
• Strong diagnostics for maintenance

Applications

• Emergency stop systems (E-Stop circuits)
• Safety gate interlocks
• Industrial machine shutdown systems
• Safety contactor control
• Robotics safety zones
• Conveyor safety systems