SIEMENS 6ES5420-4UA14 Digital Input Module | Replacement, Equivalent & Selection Guide
The SIEMENS 6ES5420-4UA14 is a 32-channel digital input module designed for the SIMATIC S5 programmable logic controller (PLC) series. It serves as the primary interface between field-level sensors, switches, and pushbuttons and the S5 central processing unit, enabling reliable discrete signal acquisition in industrial automation systems.
This page is your authoritative reference for the 6ES5420-4UA14: full technical specifications, verified replacement and equivalent models, system compatibility, and a structured selection guide to help you source the right module with confidence.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 6ES5420-4UA14 |
| Manufacturer | SIEMENS |
| Series | SIMATIC S5 |
| Module Type | Digital Input (DI) |
| Number of Inputs | 32 channels |
| Input Voltage | 24 V DC |
| Input Current (per channel) | approx. 7 mA |
| Signal Level “1” | 13–33 V DC |
| Signal Level “0” | 0–5 V DC |
| Isolation | Optocoupler isolation, group-wise |
| Backplane Bus | S5 parallel bus (U-bus) |
| Mounting | S5 expansion rack / central rack |
| Dimensions (W×H×D) | approx. 25 × 290 × 210 mm |
| Weight | approx. 300 g |
| Operating Temperature | 0–60 °C |
| Storage Temperature | −40–70 °C |
| Degree of Protection | IP20 |
| Certifications | CE, UL (original SIEMENS) |
⚠ Key parameters affecting replacement decisions: input channel count (32), voltage level (24 V DC), bus interface (S5 U-bus), and optocoupler isolation grouping. Any substitute must match these to ensure drop-in compatibility.
Compatible Replacement & Equivalent Models
Buyers searching for a 6ES5420-4UA14 replacement, equivalent, or substitute typically fall into three scenarios. Review each category carefully before making a sourcing decision.
1. Direct Drop-in Replacements (Same Form, Fit & Function)
- 6ES5420-4UA13 — Earlier hardware revision of the same module. Functionally identical in most S5 installations; verify firmware compatibility with your CPU.
- 6ES5420-4UA12 — Older revision; suitable for legacy systems where revision-specific features are not required. Confirm connector pinout before installation.
Prerequisite: Same S5 rack slot, same 24 V DC field wiring. No software changes required.
2. Functional Equivalents (Same Function, Different Form Factor or Addressing)
- 6ES5421-8MA11 — 32-channel DI module with similar electrical characteristics; may require address switch reconfiguration.
- 6ES5430-4UA12 — 16-channel DI variant; suitable when only partial channel count is needed. Two units may be used to replicate 32-channel capacity.
Note: Functional equivalents may require minor PLC program address mapping changes. Consult your system integrator.
3. Cross-Brand Alternatives (Migration / Modernization Path)
- SIEMENS ET 200M with SM 321 (6ES7321-1BL00-0AA0) — SIMATIC S7-300 equivalent DI module; requires S5→S7 migration project and hardware adapter rack.
- Third-party S5-compatible DI modules (e.g., from Vipa/Yaskawa or compatible OEM suppliers) — verify bus timing and isolation specs against OEM datasheet before deployment.
⚠ Cross-brand alternatives are migration solutions, not drop-in replacements. Always validate with a pilot installation before full deployment.
Why Choose the Original Model
- Precision & Signal Integrity: Factory-calibrated optocoupler thresholds ensure consistent 24 V DC signal discrimination across all 32 channels, minimizing false triggers in noisy industrial environments.
- OEM Certification: Original 6ES5420-4UA14 units carry CE and UL certifications, meeting IEC 61131-2 compliance requirements for safety-critical installations.
- Guaranteed Bus Compatibility: Engineered specifically for the S5 U-bus protocol; no timing deviations or handshake issues that can occur with third-party alternatives.
- Full Technical Support: SIEMENS and authorized distributors like Konmask provide datasheet access, firmware history, and application engineering support for original modules.
- Warranty & Traceability: Sourced through verified channels, each unit comes with documented provenance and warranty coverage, critical for regulated industries.
- Long-Term Spare Parts Ecosystem: Original modules integrate seamlessly with existing S5 spare parts inventory, reducing risk during unplanned maintenance events.
Typical Applications
- Automotive Manufacturing: Body-in-white assembly lines — monitoring limit switches, door sensors, and safety interlocks on transfer presses.
- Chemical & Petrochemical Plants: Process control panels — reading valve position feedback, level switches, and emergency stop signals.
- Power Generation: Turbine control systems — acquiring discrete status signals from protection relays and circuit breaker auxiliary contacts.
- Water & Wastewater Treatment: Pump station automation — monitoring float switches, flow switches, and motor run/fault status.
- Food & Beverage Processing: Conveyor and filling line control — detecting product presence, cap detection, and safety guard status.
- Building Automation & HVAC: Legacy BMS integration — reading digital status from damper actuators, fan contactors, and fire alarm interfaces.
System Compatibility
The 6ES5420-4UA14 is designed for use within the SIMATIC S5 ecosystem. Verified compatible components include:
- 6ES5095-8MA02 — S5-95U CPU unit; primary host controller for compact S5 systems.
- 6ES5100-8MA02 — S5-100U central rack; standard mounting rack for this DI module.
- 6ES5183-3AA11 — S5 expansion unit interface module; enables multi-rack configurations.
- 6ES5308-3UA11 — S5 power supply module (24 V DC); provides regulated bus power for the rack.
- 6ES5490-8MB11 — S5 front connector; required field wiring termination for the 6ES5420-4UA14.
- 6ES5700-8MA11 — STEP 5 programming software; used for I/O address configuration and diagnostics.
Selection Guide
Answer these three questions to confirm the 6ES5420-4UA14 — or its replacement — is the right choice for your application:
Q1: Is your existing PLC platform SIMATIC S5 (S5-95U, S5-100U, S5-115U, S5-135U, or S5-155U)?
If yes, the 6ES5420-4UA14 is a direct fit. If you are on S7-300/400 or S7-1500, contact Konmask for a migration-path recommendation.
Q2: Do your field devices output 24 V DC discrete signals (sensors, limit switches, pushbuttons)?
If yes, this module is electrically compatible. If your signals are 120 V AC or 230 V AC, a different DI module variant is required — contact us before ordering.
Q3: Do you require all 32 input channels, or would a 16-channel module suffice?
If 32 channels are needed, the 6ES5420-4UA14 is the correct selection. If 16 channels are sufficient, the 6ES5430-4UA12 may offer a cost-optimized alternative.
📩 Not sure? Contact Konmask at support@konmask.com — our engineers respond within 24 hours with a confirmed compatibility assessment.
Quality Assurance & Sourcing
Sourcing Channels: Konmask sources the 6ES5420-4UA14 exclusively through authorized SIEMENS distributors, certified industrial surplus channels with full traceability, and verified OEM refurbishment partners. We do not source from unverified grey-market brokers.
4-Step Inspection Process:
- Visual & Physical Inspection: Check for counterfeit markings, board damage, corrosion, and connector integrity against OEM reference samples.
- Functional Test: Each channel is exercised under 24 V DC test signals to verify input threshold response and optocoupler switching.
- Bus Communication Test: Module is seated in an S5 test rack and polled by a reference CPU to confirm correct data register response.
- Documentation Review: Serial number, date code, and hardware revision are logged and cross-referenced against SIEMENS production records where available.
Available Documentation: Test report, product photos (all sides), CE declaration of conformity (original units), and packing list with serial numbers — provided upon request with every order.
How to Order
- Submit Your Inquiry: Email support@konmask.com or call +0086 19859288691 with your part number (6ES5420-4UA14), required quantity, and any specific hardware revision requirements.
- Receive Confirmation & Quote: Our team will confirm stock availability, hardware revision, condition (new / tested surplus), and provide a formal quotation within 24 hours.
- Place Order & Ship: Upon order confirmation, we arrange secure packaging and dispatch with full tracking. Export documentation and customs invoices are provided for international shipments.
Replacement & Compatibility FAQ
Q: Can the 6ES5420-4UA13 directly replace the 6ES5420-4UA14?
A: In most S5 installations, yes — the -4UA13 is an earlier hardware revision with the same electrical and bus interface specifications. However, if your system uses revision-specific firmware features, verify with your SIEMENS documentation or contact Konmask before substituting.
Q: Is there an S7-series equivalent or substitute for the 6ES5420-4UA14?
A: The functional equivalent in the S7-300 platform is the SM 321 (6ES7321-1BL00-0AA0), a 32-channel 24 V DC DI module. However, this is not a drop-in substitute — it requires an S5-to-S7 hardware migration, rack replacement, and STEP 7 reprogramming. Konmask can support this migration project end-to-end.
Q: Are third-party compatible modules a safe substitute for the original SIEMENS 6ES5420-4UA14?
A: Third-party S5-compatible DI modules can be functional substitutes in non-safety-critical applications, but they carry risks: unverified bus timing, no OEM certification, and limited technical support. For safety-rated or regulated installations, Konmask strongly recommends sourcing original or OEM-refurbished SIEMENS modules to maintain system integrity and compliance.
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