The SM 1231 module, part number 6ES7 231-4HD32-0XB0, seamlessly expands the SIMATIC S7-1200 PLC by adding four differential analog inputs. It supports both voltage and current signals, delivering precise and reliable analog data critical for modern automation systems.
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Key Technical Specifications
Feature Specification
Inputs 4 differential analog inputs, configurable in groups of two as voltage or current
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Supported Ranges Voltage: ±10 V, ±5 V, ±2.5 V
Current: 0–20 mA, 4–20 mA
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Resolution 12 bits + sign (13-bit ADC)
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Accuracy ±0.1 % at 25 °C; up to ±0.2 % across –20 to +60 °C of full scale
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Conversion Time ≤ 625 µs for all channels
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Input Impedance Voltage ≥ 9 MΩ; Current ~280 Ω
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Overload Protection Voltage max: ±35 V; Current max: ±40 mA
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Noise Rejection 40 dB suppression from DC to 60 Hz; Supports 10/50/60/400 Hz filtering
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Input Filtering Parameterizable: None, Low, Medium, High smoothing
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Diagnostics Smart alerts: Overflow/Underflow, 24 V supply low, open-wire detection (in 4–20 mA mode), status LEDs
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Power & Consumption From 24 V DC: ~45 mA
From SM-bus (5 V): ~80 mA
Power loss: ~1.5 W
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Mechanical Specs Size: 45 × 100 × 75 mm (W×H×D); Weight: ~180 g
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Environmental Conditions Operating: –20 °C to +60 °C (horizontal); –20 °C to +50 °C (vertical). Storage: –40 °C to +70 °C. Humidity: ≤95 % non-condensing. Free-fall: ≤0.3 m in packaging
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Certifications IP20, CE, UL/cULus, CSA, FM, RCM, KC, Marine
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Cable Length Up to 100 m with shielded, twisted-pair wiring
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Wiring Connector Gold-plated front connectors (X10/X11) for 24 V and input channels; see module wiring diagrams
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Engineering Highlights

Flexible Analog Interfacing: Supports both voltage and current inputs, configurable in pairs—ideal for diverse sensor and instrumentation compatibility.

High-Resolution Precision: With 13-bit ADC and minimal temperature drift, suitable for accurate process monitoring.

Fast, Filtered Response: Rapid conversion times paired with adjustable noise filtering allow agile yet stable readings.

Comprehensive Diagnostics: Onboard features and LED indicators simplify troubleshooting and enhance operational safety.

Compact and Energy-Efficient: Slim form factor and low energy draw maintain efficient panel space utilization.

Rugged and Certified: Meets industrial ruggedness standards and safety certifications for reliable field deployment.

Ideal Applications

Industrial analog signal collection: temperature, pressure sensors, flow transmitters.

Process control loops requiring fine-scale analog precision.

Retrofits or expansions in S7-1200 systems needing analog inputs without extra amplifiers.

Long-distance signal acquisition in industrial environments—up to 100 m runs.

Summary

The SM 1231 4-channel Analog Input Module (6ES7 231-4HD32-0XB0) offers versatile, high-precision analog acquisition for SIMATIC S7-1200 systems. It’s engineered for flexible signal handling, built-in diagnostics, and efficient space and power usage—making it a robust addition for modern industrial automation.