Line Down? Emergency Support
// Collect your data Capture
// Protect your data & assets Command Centre
PricingSecurityComplianceParts lifecycle
Connect
Packages & pricingLine down? Emergency support
// Capacity & projects Shift Hero Projects Control panels
// ECS IndustriesCase StudiesResourcesAboutClients
Book a Meeting →

Siemens SIMATIC S7-400 · Digital Input Module

Siemens 6ES7421-1BL00-0AA0

The 6ES7421-1BL00-0AA0 is no longer supplied by Siemens. If one fails, finding a replacement quickly is what matters.

  1. Active RolloutSold and supported normally
  2. Phase OutRetirement announced, still orderable
  3. CancellationNormal sale ended, spares may remain
  4. Total DiscontinuationNo manufacturer supply or repair

ECS stage: Total Discontinuation.

Is the Siemens 6ES7421-1BL00-0AA0 discontinued?

On ECS's lifecycle assessment, the 6ES7421-1BL00-0AA0 is discontinued and no longer supplied by Siemens.

Source: ECS lifecycle assessment, based on ECS's internal lifecycle data in Command Centre. Last checked . Always confirm a specific part's status with the manufacturer before buying or planning a migration.

What Total Discontinuation means for you

The manufacturer has finished with the part. You may still find one through surplus or refurbished sellers, or in another site's stores, but that is not a supply chain. Knowing where your units are, and where a spare might be, is what shortens the stoppage when one fails.

How ECS defines Total Discontinuation · all four lifecycle stages

Before replacing an input module

For an input module we would record the field voltage, sink/source arrangement, commons, channel allocation and PLC addresses before considering an alternative.

Modern I/O can accept the same nominal signals but use different terminal layouts, isolation groups or addressing, which means a small module change can create wiring and software work. Photographing the terminations and exporting the I/O configuration now can save a lot of diagnosis during a breakdown.

ECS engineering guidance

6ES7421-1BL00-0AA0 part details

Manufacturer
Siemens
Range
SIMATIC S7-400
Name
SM 421 DIGITAL INPUT MODULE
Summary
SIMATIC S7-400, SM 421 DIGITAL INPUT MODULE, OPTIC. ISOLATED, 32 DI, 24V DC

Common questions about the 6ES7421-1BL00-0AA0

Is the Siemens 6ES7421-1BL00-0AA0 discontinued?

On ECS's lifecycle assessment, the 6ES7421-1BL00-0AA0 is discontinued and no longer supplied by Siemens.

Can I still buy a 6ES7421-1BL00-0AA0?

Not from Siemens. Surplus and refurbished sellers may have stock; check provenance and test before fitting.

An ECS engineer capturing a control panel on a tablet: PLC, drive and power supply identified and synced to Command Centre

Know where every unit is before one fails.

A Capture audit finds every 6ES7421-1BL00-0AA0 on your site, photographs it where it sits and checks it against manufacturer lifecycle status, so you know your exposure and where your spares are before a failure stops a line.

  • Every device located, photographed and lifecycle-checked
  • Findings report, plus a populated Command Centre
  • No production downtime
See how Capture works

Other SIMATIC S7-400 parts

All Siemens parts · All manufacturers