Beckhoff KS3222 Bus Terminal 2-Channel Analog Input

Description

Acquisition of high-precision temperature measurements in industrial automation environments is handled directly by the Beckhoff KS3222, a 2-channel analog input terminal designed for resistive sensors. The Beckhoff KS3222 enables direct connection of resistance thermometers, including Pt100, Pt1000, Ni100, and Ni1000 sensors, utilizing a highly stable 4-wire connection technology to eliminate errors from line resistance. This terminal features pluggable wiring levels, making it highly serviceable for modular control cabinets using the Beckhoff K-bus system. Featuring built-in open-circuit recognition and a dedicated 50 Hz filter, this module ensures reliable signal integrity and high-resolution temperature conversion in harsh industrial environments.

Features

• Dual-Channel Input: Supports two independent RTD or resistance measurement sensors.
• Pluggable Wiring Level: The KS series housing allows pre-wired terminal blocks to be plugged or unplugged easily for rapid commissioning and maintenance.
• 4-Wire Connection Technology: Minimizes line resistance measurement errors for elevated precision over long cable runs.
• Broad Sensor Compatibility: Direct integration of Pt100, Pt200, Pt500, Pt1000, Ni100, Ni120, Ni1000, KTY, and potentiometer measurements.
• High-Resolution Digitization: Provides a 0.01 degC resolution per digit with a fast typical conversion time of 50 ms.
• Robust Electrical Isolation: Delivers 500 V electrical isolation between the K-bus and the signal channels.
• Hazardous Location Certified: ATEX Zone 2 Ex marking (II 3 G Ex nA IIC T4 Gc) for explosive environments.

Applications

• Precision Temperature Control: Heat treatment, plastics processing, and industrial furnace monitoring.
• Process Engineering: Chemical processing plants requiring ATEX-certified temperature acquisition.
• HVAC and Climate Automation: Environmental monitoring in data centers and storage facilities.
• Mechanical Engineering: Integrated temperature sensing for motor windings, bearings, and hydraulic systems.

Technical Specifications

Wiring Connection Specifications

Empirical Engineering Insights

Alternative Models & Compatibility

The KS3222 is functionally identical to the standard Beckhoff KL3222. The key structural difference lies in the connection interface: the KS3222 features a pluggable wiring level, allowing the terminal block connector to be removed while retaining field wiring. This minimizes downtime during physical module replacement. This terminal requires a standard K-bus backplane and can be integrated seamlessly with any Beckhoff BK-series or BC-series Bus Couplers without modifying PLC code or TwinCAT configurations.

Application Pitfalls & Engineering Notes

To ensure high-precision readings down to 0.01 degC, the measuring current is kept at a low typical rate of 0.5 mA. This design constraint is essential to minimize the self-heating of small-mass RTD sensors (such as Pt100) within the medium. However, because the measuring current is low, the signal path is more susceptible to high-frequency electromagnetic interference. When routing RTD wiring through the same cable tray as variable frequency drives (VFDs) or heavy inductive loads, you must utilize shielded twisted pair (STP) cables to avoid signal degradation.

Commissioning & Wiring Tips

When configuring the KS3222 under TwinCAT (2.x or 3.x), the sensor type must be matched to the register settings of the terminal. The factory default setting is optimized for Pt100 sensors. If you are using Ni100 or potentiometer modes, ensure you execute the configuration via register communication (e.g., using KS2000 software or PLC blocks) before putting the loop into auto-control. For 4-wire configuration, ensure all four pins are properly jumpered directly at the RTD sensor element rather than at the control cabinet terminal block to compensate fully for lead wire resistance.

Installation Guidelines