Product Overview

The Allen-Bradley 1756-IF8 is a high-density analog input module engineered for the ControlLogix® platform. It provides eight non-isolated differential inputs, designed to interface with various field-side instruments. By converting high-resolution analog signals into digital data, the 1756-IF8 allows Logix5000™ controllers to monitor and regulate critical process variables such as flow, temperature, pressure, and level.

Utilizing advanced Sigma-Delta analog-to-digital conversion, the 1756-IF8 ensures superior signal integrity and noise rejection. This module is built on Producer/Consumer technology, which allows input data to be multicasted across the backplane to multiple controllers simultaneously. This decentralized data sharing architecture enhances system efficiency and reduces the communication load on the primary processor.

Signal Compatibility and Configuration

The 1756-IF8 is highly versatile, supporting multiple voltage and current ranges that are software-configurable on a per-channel basis. This eliminates the need for physical jumpers and simplifies commissioning.

• Voltage Ranges: ±10V, 0–10V, 0–5V, and 1–5V.

• Current Ranges: 0–20 mA and 4–20 mA.

• Digital Conversion: 16-bit resolution provides precise granularity for sensitive process loops.

• On-board Scaling: Automatically converts raw counts into engineering units (e.g., PSI, °C, GPM), reducing the computational burden on the controller.

The module also features real-time hardware diagnostics, including over-range/under-range detection and process alarms (high/high-high/low/low-low). These features allow the system to react instantly to field-side faults or process deviations.

Technical Specifications

• Manufacturer: Allen-Bradley (Rockwell Automation)

• Model Number: 1756-IF8

• Module Type: Analog Input (Voltage/Current)

• Inputs: 8 Channels (Differential)

• Backplane Current (5.1V): 150 mA

• Backplane Current (24V): 40 mA

• Power Dissipation: 2.3 Watts (Maximum)

• Thermal Dissipation: 7.84 BTU/hr

• Resolution: 16 Bits

• Input Impedance: >10 MΩ (Voltage), 249 Ω (Current)

• Operating Temperature: 0°C to 60°C (32°F to 140°F)

• Vibration/Shock: 2g @ 10–500Hz / 30g Operational

• Dimensions: 14.5 x 3.5 x 13.0 cm

• Weight: 0.9 kg

Maintenance and System Integration

• Hot-Swappable: Supports RIUP (Remove and Insert Under Power), permitting hardware maintenance without shutting down the entire chassis.

• Field Connection: Requires a 20-pin or 36-pin Removable Terminal Block (RTB), such as the 1756-TBNH or 1756-TBSH, which must be ordered separately.

• Filtering: Digital notches filters are user-selectable (50Hz, 60Hz, 250Hz, 500Hz) to eliminate localized electrical noise interference.

• Chassis Compatibility: Fully compatible with all standard ControlLogix 1756-A series chassis and communication adapters for remote I/O applications.