HARDY 1756-2WS Weigh Scale Module ControlLogix-Compatible Weighing I/O for Industrial Process Control

Technical Dossier

Product Details And Specifications

HARDY 1756-2WS Series Technical Notes

The Evolution of 1756-2WS Architecture

Hardy Instruments (acquired by Mettler Toledo in 2007) introduced the 1756-series weigh scale modules as a direct response to the industry shift from standalone weight controllers toward embedded, backplane-native I/O. Early Hardy weight controllers such as the HI 2110 and HI 3010 communicated via RS-232 or DeviceNet, requiring a dedicated serial interface module in the ControlLogix rack. The 1756-2WS eliminated this dependency by occupying a standard 1756 I/O slot and communicating over the ControlLogix backplane at full rack speed.

1756-2WS Full Catalog & Functionalities (SKU List)

The following SKUs represent the core Hardy / Mettler Toledo 1756-platform and directly compatible weigh scale module range. Each entry reflects a verified, commercially documented part number.

1756-2WS: Dual-channel ControlLogix weigh scale I/O module, C2 & WAVERSAVER®
1756-1WS: Single-channel ControlLogix weigh scale module, C2 electronic calibration
HI 1756-2WS: OEM-labeled variant; functionally identical to 1756-2WS, Hardy catalog prefix
HI 1756-1WS: Single-channel OEM-labeled variant for ControlLogix platform
HI 6600-2WS: Next-generation dual-channel weigh scale module, successor platform
HI 6600-1WS: Next-generation single-channel weigh scale module
HI 3010: Standalone weight controller, RS-232/DeviceNet, predecessor to 1756-series
HI 2110: Panel-mount weight controller, analog output, legacy predecessor
HI 4050: Rate-of-change / flow rate weight controller, compatible with 1756 AOI
HI 4060: Batching/blending weight controller, multi-setpoint, standalone
HI 6300: Intrinsically safe weight transmitter, ATEX/IECEx rated
HI 6500: Weight/force measurement module, high-speed dynamic weighing
HI 2151/30WC: Compact weight controller, DIN-rail mount, Modbus RTU
HI 2151/30WS: Weight controller with serial output, legacy ControlNet interface
HI 9000MS: Multi-scale junction box with C2 diagnostics, field-mount
HI 215IT: Intrinsically safe weight transmitter, 4–20 mA analog output
HI 2160RC: Remote display/controller for Hardy weigh systems, panel-mount
HI 4050/30: Rate controller with 30-point linearization, process industry variant
1756-DHRIO: Allen-Bradley DH+ / Remote I/O bridge (required for legacy Hardy DeviceNet integration)

Quality Control for the 1756-2WS Range

The 1756-2WS presents specific test challenges due to its dual-function role as both an analog signal conditioner (load cell excitation and millivolt input) and a digital backplane I/O module. DriveKNMS applies a multi-stage test protocol to every unit processed:

Stage 1 — Backplane Communication Test: The module is seated in a live 1756 chassis with an L7x or L8x controller. RSLogix 5000 / Studio 5000 is used to verify module identity, firmware revision readback, and fault-free I/O tree registration.
Stage 2 — Load Cell Excitation Verification: Excitation voltage output (typically 10 VDC) is measured at the field wiring terminals under no-load and simulated load conditions using a precision resistive load cell simulator.
Stage 3 — A/D Conversion Accuracy: A calibrated millivolt source is applied across the signal inputs. Weight register values are read via the controller tag database and compared against reference values to verify A/D linearity within ±0.01% of full scale.
Stage 4 — C2 Electronic Calibration Cycle: A full C2 calibration sequence is executed using Hardy's documented procedure to confirm EEPROM write integrity and calibration data retention.
Stage 5 — WAVERSAVER® Filter Validation: Simulated vibration noise is injected via the signal input. Filter response is verified against Hardy's published attenuation specifications.
Stage 6 — Thermal Soak: Units are operated at elevated ambient temperature (50°C) for a minimum of 4 hours to screen for latent component failures prior to shipment.