6ES7431-1KF20-0AB0 Siemens S7-400 Analog Input Module

6ES7431-1KF20-0AB0 — Siemens SIMATIC S7-400 Analog Input Module SM 431

Key Technical Specifications

• Brand: Siemens — a global leader in industrial automation.
• Model: 6ES7431-1KF20-0AB0 — part of the SIMATIC S7-400 family.
• Category: Analog input module SM 431, isolated, 8 AI channels.
• Resolution: 14-bit with overrange (including sign).
• Cycle time: 0.416 ms for all 8 channels.
• Supply voltage: 24 V DC load voltage (only for 2-wire transmitters).
• Reverse polarity protection: Yes — protects the module from wiring errors.
• Input current: Max. 200 mA from load voltage L+ (no load).
• Power loss: Typically 4.9 W.

Analog Input Ranges and Measurement

• Voltage ranges: 1 V to 5 V, -1 V to +1 V, and -10 V to +10 V.
• Input resistance: 10 MΩ for 1–5 V and ±1 V; 100 kΩ for ±10 V.
• Current ranges: ±20 mA and 4–20 mA.
• Input resistance: 50 Ω for ±20 mA; 50 kΩ for 4–20 mA.
• Resistance range: 0 to 600 ohms — ideal for resistance-type transmitters.
• Constant measurement current: Typically 1.67 mA for resistance measurement.
• Permissible input voltage: Max. 18 V continuous (75 V for 1 ms, ratio 1:20).
• Permissible input current: Max. 40 mA permanent.

Accuracy, Speed, and Noise Immunity

• Temperature error: ±0.03 %/K relative to input range.
• Operational error limit: ±0.7 % for ±1 V; ±0.9 % for ±10 V and 1–5 V.
• Current error: ±0.8 % for ±20 mA and 4–20 mA ranges.
• Resistance error: ±1 % relative to input range.
• Basic error at 25 °C: ±0.6 % for ±1 V; ±0.75 % for ±10 V and 1–5 V.
• Interference suppression: Selectable for none, 400 Hz, 60 Hz, or 50 Hz.
• Input filter time constant: 15 µs — helps reject high-frequency noise.
• Basic execution time: 0.42 s for all channels released.

Isolation, Diagnostics, and Environmental Durability

• Potential separation: Yes — between analog inputs and backplane bus.
• Channel isolation: No isolation between individual channels.
• Load voltage isolation: Yes — between channels and load voltage L+.
• Isolation test: 2120 V DC between bus and analog section.
• Diagnostics function: No — this module does not provide channel diagnostics.
• Shielded cable length: Max. 200 m for reliable signal transmission.
• Dimensions: 25 mm wide, 290 mm high, 210 mm deep.
• Weight: Approximately 500 g.

Installation Guide

• Mount the module in a Siemens S7-400 rack with proper backplane bus connection.
• Connect 24 V DC load voltage only when using 2-wire transmitters.
• Use shielded twisted-pair cables to reduce electrical noise and interference.
• Keep cable length under 200 m for resistance and voltage measurements.
• Verify reverse polarity protection works by checking wiring before power-up.
• Configure input ranges and interference suppression in STEP 7 software.
• Allow the module to warm up to 25 °C for best accuracy performance.
• Do not exceed 18 V continuous input voltage to avoid permanent damage.

Package Contents

• 1 × Siemens 6ES7431-1KF20-0AB0 analog input module SM 431.
• 1 × Quick reference guide for wiring and configuration.
• 1 × Protective shipping carton with anti-static foam.

Shipping and Support

• We ship via FedEx, UPS, and DHL — choose your preferred courier at checkout.
• Our stock is ready for immediate dispatch within 5 days after payment.
• We accept returns within 30 days for unused items in original packaging.
• Contact us for bulk orders or technical questions about this Siemens module.

FAQ

• Q: What is the resolution of the 6ES7431-1KF20-0AB0?
  A: It provides 14-bit resolution with overrange, including the sign bit.
• Q: Can this module measure resistance thermometers?
  A: No, it does not support thermocouples or resistance thermometers. It supports resistance measurement from 0 to 600 ohms.
• Q: How many analog inputs does this module have?
  A: It has 8 analog input channels, but only 4 channels work for resistance measurement.
• Q: What is the cycle time for all 8 channels?
  A: The cycle time is 0.416 ms, which is fast for industrial control loops.
• Q: Does this module support 2-wire and 4-wire transmitters?
  A: Yes, it supports 2-wire, 3-wire, and 4-wire connections for current and resistance measurement.
• Q: What is the maximum shielded cable length?
  A: You can use shielded cables up to 200 meters long without signal degradation.
• Q: Is the module isolated between channels?
  A: No, there is no isolation between individual channels, but it is isolated from the backplane bus.
• Q: What is the power loss of this module?
  A: The typical power loss is 4.9 W, which is moderate for a 8-channel analog input module.
• Q: Can I use this module with a 24 V DC supply?
  A: Yes, 24 V DC load voltage is only required when powering 2-wire transmitters.
• Q: How do I suppress interference at 50 Hz or 60 Hz?
  A: You can parameterize the interference suppression frequency in STEP 7 software.

Contact Information

• Inquiries: sales@nex-auto.com
• Phone/WhatsApp: +86 153 9242 9628
• Partner: NexAuto Technology Limited