1756-WS | AB Allen Bradley | Hardy Instruments 1756-WS Weigh Scale Module

Product Summary

The Allen-Bradley 1756-WS is a Weigh Scale Module manufactured by Hardy Process Solutions for the Rockwell Automation ControlLogix platform. It is a single-slot, single-channel module that mounts directly into a ControlLogix chassis, reading weight and diagnostic data from strain gauge load cells and transmitting it over the backplane to the ControlLogix processor. The module eliminates the need for external Ethernet switches or routers, reducing installation cost and complexity.

Core Specifications

• Model Number: 1756-WS
• Type: Single-Channel Weigh Scale Module
• Platform: ControlLogix (1756 chassis)
• Resolution: Over 8,388,608 counts (A/D converter)
• Update Rate: 50 times per second
• Signal Range: 0 to 15.3 mV differential
• Load Cell Excitation: 5 VDC (supports up to four 350 ohm load cells)
• Backplane Current: <1 A at 5 VDC; 0.0125 A at 24 VDC (with 4×350 ohm load cells)
• Backplane Power: <5 W at 5 VDC; <0.3 W at 24 VDC
• Manufacturer: Hardy Process Solutions (for Allen-Bradley / Rockwell Automation)

Electrical & Functional Characteristics

• WAVERSAVER®: Eliminates effects of plant vibration as low as 0.25 Hz; five selectable cutoff frequencies (0.25, 0.5, 1.0, 3.5, 7.5 Hz)
• C2® Electronic Calibration: Calibrates without test weights using C2-certified load sensors; also supports traditional hard calibration
• INTEGRATED TECHNICIAN® (IT): Built-in system diagnostics for troubleshooting individual load cell voltages and weights
• Common-Mode Rejection: 110 dB at or below 60 Hz
• Common-Mode Voltage Range: 2.5 VDC maximum (with respect to earth ground)
• Status Indicators: Bi-color LEDs for scale data and module status

System Integration & Compatibility

• Primary Platform: Allen-Bradley ControlLogix 1756 chassis
• Software: RSLogix 5000 / Studio 5000 Logix Designer with Add-On-Profile (AOP) support
• Communication: Producer/consumer technology over ControlLogix backplane
• Hot Swap: Supports removal and insertion under power (RIUP)
• Remote Rack Support: Can operate in remote chassis via ControlNet link
• Related Parts: 1756-2WS (dual-channel version), 1756-RTA (Remote Termination Assembly), HI 215IT (Junction Box)

Environmental & Operational Limits

• Operating Temperature: 0°C to 60°C (32°F to 140°F)
• Storage Temperature: -40°C to +85°C (-40°F to 185°F)
• Humidity: 0% to 90% RH, non-condensing
• Approvals: CE, UL, CUL (pending)

Industrial Applications

Widely deployed in batching, blending, filling/dispensing, check weighing, force measurement, level-by-weight, and weight rate monitoring applications across food & beverage, pharmaceuticals, chemicals, plastics, and general manufacturing industries.

Frequently Asked Questions

What is the 1756-WS used for?

It is a single-channel weigh scale module for ControlLogix systems, reading weight data from strain gauge load cells and transmitting it directly to the PLC processor over the chassis backplane.

How many load cells can it support?

Up to four 350 ohm load cells with the internal 5 VDC excitation. Additional load cells require an external power supply.

What is the difference between 1756-WS and 1756-2WS?

The 1756-WS is a single-channel module. The 1756-2WS is a dual-channel module supporting up to eight load cells (four per channel) in a single slot.

How do I calibrate the module?

C2 electronic calibration requires C2-certified load sensors and is triggered by pressing "The Button" on the module front or via ladder logic command. Traditional hard calibration with certified test weights is also supported.

What are the related part numbers?

• 1756-WS — Single-channel weigh scale module (this part)
• 1756-2WS — Dual-channel weigh scale module
• 1756-RTA — Remote Termination Assembly
• HI 215IT — Junction Box with IT diagnostics