Siemens 6ES5431-4UA12 Input Module | 16 Ch, 24V DC, 4.7 kΩ

This digital input module captures sixteen channels of 24V DC field signals. The Siemens 6ES5431-4UA12 belongs to the SIMATIC S5 product family. You can connect limit switches, proximity sensors, and pushbuttons directly. Its high channel density saves valuable space inside control cabinets.

Physical Dimensions and Hardware Layout

The Siemens 6ES5431-4UA12 measures 25.0 cm in overall width. Its total depth reaches 21.5 cm including the front connector. This digital input module weighs approximately 0.78 kg. A metal housing provides excellent shielding against electrical noise. One green LED indicates backplane power status. Additionally, sixteen red LEDs show each channel’s active input state.

Electrical Input Specifications

Each input channel operates at 24V DC nominal voltage. The Siemens 6ES5431-4UA12 provides a typical input resistance of 4.7 kΩ. Channel turn‑on voltage requires a minimum of 15V DC. Conversely, turn‑off voltage occurs below 5V DC. Built‑in filtering removes electrical noise effectively. The module divides inputs into two isolated groups of eight channels.

Parameter	Specification
Number of Channels	16
Product Family	SIMATIC S5
Input Type	Sink/source (configurable)
Nominal Voltage	24V DC
Input Voltage Range	20.4V to 28.8V DC
On‑State Threshold	≥ 15V DC
Off‑State Threshold	≤ 5V DC
Input Resistance	4.7 kΩ typical
Input Delay (On→Off)	3 ms typical
Input Delay (Off→On)	3 ms typical
Dimensions (W x H x D)	250 mm x 75 mm x 215 mm
Weight	0.78 kg (1.72 lbs)
Terminal Type	20‑pin front connector (sold separately)
Wire Size	0.5 to 2.5 mm²
Backplane Current Draw	180 mA @ 5V DC
Power Dissipation	1.2 W typical
Internal Energy Storage	47 µF capacitor for status retention
Isolation Voltage	500 Vrms groups‑to‑backplane
Number of Components	1 main board, 1 input filter network
LED Indicators	1 green (power), 16 red (channels)
Operating Temperature	0°C to +60°C

Energy Storage and Input Stability

Internal capacitors maintain input status during brief power dips. The Siemens 6ES5431-4UA12 stores channel states for up to 10 ms. This storage prevents false triggering during short interruptions. Consequently, the CPU reads stable input values at all times.

Filtering and Noise Immunity

This module includes software‑selectable input filters for noise rejection. The Siemens 6ES5431-4UA12 rejects voltage spikes shorter than 1 ms. The filter time setting affects the input delay value. Use the longer filter setting for noisy environments. Use the shorter setting for high‑speed input signals.

Isolation and Channel Grouping

This module groups inputs into two isolated banks of eight channels. Each bank shares a common return terminal. The isolation withstands 500Vrms between banks and the backplane. This design protects the main controller from field wiring faults. Therefore, system reliability improves significantly in industrial environments.

Wiring and Installation Guidelines

Use the 20‑pin front connector for all field wiring connections. The Siemens 6ES5431-4UA12 accepts solid or stranded wires from 0.5 to 2.5 mm². Connect the common return for each input bank separately. Proper grounding reduces electrical noise significantly. Label each wire clearly for future maintenance.