Allen-Bradley 1734-IB8S | POINT I/O Guard I/O Safety Input Module

Product Description

The 1734-IB8S (Part Number: 1734-IB8S) is a high-density safety input solution designed for the Allen-Bradley POINT I/O platform. This module is engineered to integrate seamlessly into SIL 3 and PLe safety applications, offering eight sinking input channels and four dedicated pulse test outputs. By utilizing CIP Safety protocol over EtherNet/IP or DeviceNet, it provides distributed safety control with advanced diagnostics for detecting short circuits and cross-channel faults in field wiring.

Technical Specifications and Hardware Parameters

• Product Brand: Allen-Bradley

• Module Identifier: 1734-IB8S

• Product Series: POINT I/O Guard I/O

• Input Quantity: 8 Safety Inputs

• Input Configuration: Current Sinking (Dry Contact or Solid State)

• Test Pulse Outputs: 4 Pulse Test Sources

• Nominal Operating Voltage: 24V DC

• Input Voltage Range: 19.2V DC to 28.8V DC

• POINTBus Current Draw: 175 mA at 5V DC

• Maximum Power Dissipation: 3.4 Watts

• Safety Certification: SIL 3 (IEC 61508) and PLe/Category 4 (ISO 13849-1)

• Thermal Performance: 2.8A total current capacity at 20°C ambient

• Compatible Terminal Bases: 1734-TB, 1734-TBS, 1734-TOP, or 1734-TOPS

• Mechanical Keying: Position 8 (Key 1) and Position 1 (Key 2)

• Enclosure Rating: IP20 Open-style for cabinet mounting

• Hardware Revision Support: Series A and Series B

Module Functional Features and Safety FAQ

How do the pulse test outputs improve circuit safety?The 1734-IB8S generates specific pulse patterns on its four test outputs. When these are wired through safety devices back to the inputs, the module can detect if a wire has been crushed, shorted to a 24V power source, or shorted to another input signal. This prevents a "stuck-on" failure which could bypass a safety function.

Can this module be used with standard 1734 adapters?No, to utilize the safety functions of the 1734-IB8S, you must use a safety-rated network adapter such as the 1734-AENTR (for EtherNet/IP) and a GuardLogix or SmartGuard controller that supports CIP Safety communications.

What is the significance of the thermal derating value?At an ambient temperature of 20°C, the module can handle a cumulative field power current of 2.8A across all channels. As the temperature inside the electrical cabinet increases toward the maximum operating limit of 55°C, the allowable current decreases. Engineers must calculate the total load of connected sensors to ensure the module remains within its safe thermal operating envelope.