Product Overview

SIMATIC S7-300 SM 331 Analog Input Module – 8-Channel, 13-Bit Resolution (6ES7331-1KF02-0AB0)
An eight-channel analog input module for the S7-300 PLC family, offering high-precision data acquisition. It supports voltage, current, resistance, and temperature sensor inputs (e.g., Pt100, Ni100) in a slim 40 mm-wide form factor—with optical isolation for the backplane.

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Technical Specifications
Attribute Details
Analog Inputs 8 isolated channels
Resolution Maximum 13-bit (including sign), per-channel programmable to 12 bits
Measurement Ranges Voltage (e.g. ±10 V, 0–10 V, ±5 V, ±50 mV), Current (0–20 mA, 4–20 mA), Resistance (up to 600 kΩ), RTDs (Pt100, Ni100, Ni1000, LG-Ni1000)
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Input Impedance Voltage: 100 kΩ; Current: 100 Ω; RTDs/Resistors: 100 MΩ
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Sampling / Conversion Basic conversion: ~66 ms; Parameterizable integration time (e.g. 50 ms)
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Accuracy Voltage/current: ±0.4–0.6 % (depending on range); Resistance: ±0.3–0.5 %; RTDs: ±0.8–1 K
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Diagnostics No channel-level diagnostics or LEDs; only backplane fault channel
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Siemens Support

Isolation Inputs are isolated from the backplane; no inter-channel isolation; tested to 500 V DC
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Connectivity Uses a 40-pin front connector
Power Draw From backplane: 5 V DC, max 90 mA; typical power dissipation: approx. 0.4 W
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Dimensions & Weight Width: 40 mm; Height: 125 mm; Depth: 117 mm; Weight: ~250 g
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Product Lifecycle & Ordering Info

Lifecycle Status: Phase-out announced (PLM PM400); discontinued since October 1, 2023
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Lead Time: Typically 1 day ex-works
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Net Weight: 0.296 kg (module + packaging)
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Package Dimensions: 12.8 × 15.1 × 5.2 cm
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Compliance: RoHS compliant since Jan 4, 2010; WEEE take-back applies. Contains lead, lead monoxide, and a REACH-listed SVHC above 0.1 % w/w
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Classification Codes: eClass 27-24-22-01; ETIM EC001420; UNSPSC 32-15-17-05
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Engineering Insight

Versatile Sensing Capabilities
Supports a wide array of inputs—voltage, current, resistance, and RTDs—making it ideal for diverse industrial measurement tasks.

High Accuracy & Configurable Performance
Offers up to 13-bit resolution and adjustable integration times to balance speed and precision.

Compact & Backplane-Isolated
Narrow width and optical isolation from the backplane make it a safe, space-efficient choice for dense I/O configurations.

Lifecycle Planning Required
With its phase-out initiated in 2023, it’s essential to plan for replacements or stock up for ongoing use in legacy systems.