Beckhoff ELX3351 EtherCAT Terminal 1-Channel Intrinsically Safe Analog Input Module

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Manufacturer: BECKHOFF
Product No.: ELX3351
Country of origin:Germany
Product Type: EtherCAT Terminal Modules
Payment: T/T, Western Union
Weight: 2000g
Dimensions: 12 mm x 100 mm x 68 mm
Shipping port: Xiamen
Warranty: 12 months

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Description

Executing high-precision force and weight measurements within hazardous areas is directly enabled by the Beckhoff ELX3351 EtherCAT Terminal. This intrinsically safe (Ex i) input module is designed for the direct connection of strain gauges and resistor measuring bridges in full-bridge configurations. Featuring high-resolution 24-bit analog-to-digital conversion, it guarantees precise signal acquisition even under demanding industrial conditions. The module integrates self-calibration mechanisms and dynamic filters to compensate for thermal drift and high-frequency mechanical vibration, making it a reliable choice for hazardous-area weighing, load cell monitoring, and process vessels.

Features

Intrinsically Safe (Ex i) Interface: Direct connection to sensors located in Zone 0/20 and Zone 1/21 environments without requiring external barriers.
High-Resolution Measurement: 24-bit analog conversion with 32-bit internal presentation for micro-volt level accuracy.
Resistor Bridge Compatibility: Optimally interfaces with full-bridge strain gauges and resistor bridges ranging from 300 Ohm to 1.5 kOhm.
Advanced Signal Filtering: Configurable 50 Hz filters and dynamic low-pass options with a typical limit frequency of 3.6 kHz.
Hardware Self-Calibration: Internal reference pathways run automatic calibration cycles to eliminate measurement errors over time and temperature.

Applications

Hazardous Weighing Systems: Direct connection to platform scales, vessel weighing systems, and silo level monitors in explosive dust or gas atmospheres.
Process Industry Automation: Tension, torque, and force measurements in chemical, oil, and gas processing lines.
Test Bench Engineering: Dynamic load monitoring and strain gauge testing in laboratory environments requiring explosive safety.

Technical Specifications Table

Parameter	Specification Value
Manufacturer	Beckhoff
Model Number	ELX3351
Number of Inputs	1 (Full bridge configuration)
Nominal Bridge Resistance	300 Ohm to 1.5 kOhm
Measuring Range UD	Max. -18 to +18 mV
Measuring Range UREF	Max. -12 to +12 V
Resolution	24 bit (32 bit internal representation)
Conversion Time	Typ. 1.6 ms
Internal Resistance	> 25 kOhm (UR, differential), > 1 MOhm (UD, differential)
Measuring Error	< +/-0.5% of full-scale value (with active self-calibration)
Current Consumption E-bus	Typ. 85 mA
Ex Markings (ATEX)	II 3(1)G Ex ec [ia Ga] IIC T4 Gc, II (1)D [Ex ia Da] IIIC, I (M1) [Ex ia Ma] I
Ex Markings (IECEx)	Ex ec [ia Ga] IIC T4 Gc, [Ex ia Da] IIIC, [Ex ia Ma] I
Operating Temperature	-25 to +60 degC
Storage Temperature	-40 to +85 degC
Dimensions (W x H x D)	12 mm x 100 mm x 68 mm
Product Weight	Approx. 60 g
Shipping Weight (Calculated)	2.0 kg (including protective industrial packaging)

Empirical Engineering Insights

Alternative Models & Compatibility

Unlike the standard EL3351 terminal designed for non-hazardous zones, the ELX3351 is built strictly for Ex i intrinsically safe loops. Standard EL series terminals and ELX series terminals cannot be mixed on the same power segment without proper physical isolation. You must use an ELX9560 or ELX9410 power feed terminal to isolate the intrinsically safe power contacts from the standard EtherCAT terminal block segment to maintain Ex certification validity.

Application Pitfalls & Engineering Notes

When deploying the ELX3351 in high-vibration applications such as mixing vessels or chemical reactors, utilize the built-in dynamic low-pass filters instead of basic averaging. If the self-calibration feature is active, minor fluctuations in loop cycle times may occur during calibration intervals (typically every few minutes). Ensure your TwinCAT control loops allow for these brief, microsecond-level calculation variances, or schedule calibrations during known process idle states.

Commissioning & Wiring Tips

To minimize measurement noise over long cable runs to the strain gauge, utilize shielded twisted-pair cables with the shield connected to the terminal housing's functional ground. Ensure safe separation distances of at least 50 mm between the intrinsically safe wiring connected to the ELX3351 and any non-intrinsically safe cabling in the control panel to comply with IEC 60079-14 standards.

Installation Guidelines

CRITICAL WARNING: De-energize all system power contacts and terminal segments before mounting, wiring, or configuring the ELX3351 terminal. Failure to isolate power can result in spark generation, compromising safety in explosive atmospheres. Verify that the power segment is isolated by an approved ELX-series power supply terminal prior to applying power.

Mount the ELX3351 on a standard 35 mm DIN rail conforming to EN 60715, securing it firmly into place with the integrated locking slide.

Ensure the double slot and key connection correctly aligns with adjacent ELX modules on the E-bus.

Strip bridge sensor connections to 8–9 mm. Use a flat-blade screwdriver to depress the spring clamps, insert the solid or ferruled conductor, and release to secure.

Perform a continuity and loop barrier check before energizing the isolated power segment via the TwinCAT system configuration.

Key Features:

#ELX Series #EtherCAT Terminals

Can I mix the ELX3351 with standard Beckhoff EL-series terminals on the same DIN rail?

Yes, but they must be physically separated. You must use an ELX9560 or ELX9410 power feed terminal to isolate the power contacts of the intrinsically safe ELX series from standard non-Ex terminals.

What is the purpose of the self-calibration feature on this terminal?

Self-calibration runs automatically at regular intervals, routing internal reference voltages to compensate for thermal drift and component aging, ensuring measuring error remains below 0.5%.

Does this terminal support 6-wire strain gauge connections?

The terminal is native to 4-wire resistor bridge connections. However, 6-wire bridges can be accommodated by running the excitation and sense lines back together at the terminal connections, though physical 4-wire configuration is recommended.

What happens if a sensor wire is broken or short-circuited?

The terminal detects out-of-range differential inputs (UD) or loss of reference voltage (UREF). TwinCAT maps these conditions as diagnostic variables in the process image for direct system-level fault signaling.

Global Express Shipping

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TECHNICAL SPECIFICATIONS

Country of origin

Beckhoff ELX3351 EtherCAT Terminal 1-Channel Intrinsically Safe Analog Input Module