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6ES7421-7DH00-0AB0

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The Siemens 6ES7421-7DH00-0AB0 is an SM 421 digital input module that brings 16 individually isolated AC/DC signals into a SIMATIC S7-400 station.
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Technical specifications for 6ES7421-7DH00-0AB0

  • Manufacturer:
    Siemens
  • Part Number:
    6ES7421-7DH00-0AB0
  • Product Family:
    Siemens Simatic S7-400
  • Product Type:
    SIMATIC S7-400 SM 421 Digital Input Module
  • Stock:
    1
  • Channel Count:
    16 digital inputs
  • Input Signal Type:
    AC/DC
  • Rated Input Voltage:
    UC 24–60 V, 47–63 Hz
  • Signal 0 Range:
    -6 to +6 V DC; 0 to 5 V AC
  • Signal 1 Range:
    ±15 to ±72 V DC; 15 to 60 V AC
  • Signal 1 Current:
    4 mA typical
  • Input Delay:
    0.5 / 3 / 10 / 20 ms, parameterizable
  • Sensor Support:
    Switches and 2-wire proximity sensors
  • Reading Polarity:
    P-reading and M-reading
  • Interrupts:
    Diagnostic and hardware interrupts, parameterizable
  • Status Indication:
    Channel LEDs plus INTF and EXTF fault LEDs
  • Shielded Cable Length:
    1,000 m maximum at 3, 10, or 20 ms
  • Electrical Isolation:
    Each input isolated; 1,500 V AC test
  • Backplane Current:
    150 mA maximum at 5 V DC
  • Weight:
    1.74 lbs (0.79 kg)
  • Estimated shipping dimensions:
    23.3×30.2×4.1cm
  • Tariff Code:
    85389091
  • Country of origin:
    Germany
  • Place of shipment:
    Xiamen,Fujian,China
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More Information

Overview Manuals Input Groups Delay Logic Alarm Routing Sensor Wiring

Features:

  • Sixteen individually isolated channels accept AC or DC field states across the UC 24–60 V design.
  • Four selectable input delays link response time to the supported field-cable length.
  • Configurable diagnostics and interrupts operate beside separate channel and fault indicators.
Siemens 6ES7421-7DH00-0AB0 concentrates isolated multi-voltage input acquisition in one S7-400 SM 421 assembly.

Its reading-polarity and sensor settings define how connected field circuits are referenced before their states reach the controller.

Delay, diagnostic, and interrupt parameters keep input filtering, fault reporting, and event handling as separate functions.

Apter Power assists with pricing and access to official manufacturer documentation for Siemens 6ES7421-7DH00-0AB0 SIMATIC S7-400 SM 421 Digital Input Module.
Siemens 6ES7421-7DH00-0AB0 SIMATIC S7-400 SM 421 Digital Input Module Manuals, Datasheets, Links Important Notice: Other accessories, manuals, cables, calibration data, software, etc. are not included with this equipment unless listed in the above stock item description. All prices are shown in USD.

6ES7421-7DH00-0AB0 Channel Organization

  • Channel separation: All 16 digital inputs are isolated individually.
  • Signal type: The same input design accepts AC or DC field states.
  • Reading polarity: P-reading and M-reading modes define the field reference.
  • Sensor connection: Switch contacts and two-wire proximity sensors are supported.

6ES7421-7DH00-0AB0 Input Filtering

  • Available settings: Input delay can be set to 0.5, 3, 10, or 20 ms.
  • Parameter method: The delay is assigned through module parameterization.
  • Shortest response: The 0.5 ms setting carries the 100 m conductor limit.
  • Extended wiring: The longer settings permit the documented shielded and unshielded cable runs.

6ES7421-7DH00-0AB0 Diagnostic Paths

  • Group diagnostics: Module diagnostic evaluation can be enabled by parameterization.
  • Diagnostic interrupt: A diagnostic event can be transferred through the S7-400 interrupt path.
  • Hardware interrupt: Input events can use the separately configured hardware-interrupt path.
  • Front indication: INTF and EXTF distinguish internal from field-side fault classes.

6ES7421-7DH00-0AB0 Field Connections

  • Contact inputs: Switch contacts connect directly to the input circuits.
  • Two-wire devices: Proximity sensors must remain within the specified quiescent-current limit.
  • Voltage bands: AC and DC operation use their stated signal-zero and signal-one ranges.
  • Cable boundary: The permissible conductor length depends on the selected input delay.
Description
Siemens 6ES7421-7DH00-0AB0 is a SIMATIC S7-400 SM 421 digital input module that acquires 16 field signals for an S7-400 automation station. The channels accept AC or DC states across the UC 24–60 V design, and each input is electrically isolated from the others.

The field reference for 6ES7421-7DH00-0AB0 can be configured for P-reading or M-reading. Switch contacts and two-wire proximity sensors feed the module, which evaluates every channel against the defined signal-zero and signal-one ranges before transferring its state to the backplane.

Response behavior on 6ES7421-7DH00-0AB0 is set with a 0.5, 3, 10, or 20 ms input delay. That choice also defines the supported conductor length, linking the required response time directly to the planned field wiring.

Diagnostic processing in 6ES7421-7DH00-0AB0 includes parameterizable group diagnostics, diagnostic interrupts, hardware interrupts, and wire-break monitoring. Channel LEDs show individual states, while INTF and EXTF separate module-side and field-side fault conditions.
Alternative Names
6ES74217DH000AB0 6ES7 421 7DH00 0AB0 6ES7 421-7DH00-0AB0 Siemens 6ES7421-7DH00-0AB0 6ES7421-7DH00-0AB0 SM 421 Siemens 6ES7421-7DH00-0AB0 Digital Input Module 6ES7421-7DHOO-OABO 6ES7421 7DH00 0AB0 S7-400 Input Module
Technical notes
Siemens 6ES7421-7DH00-0AB0 requires the input delay to be selected with the planned conductor length. Configure P-reading or M-reading to match the field-signal reference.
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FAQS

The following is a list of questions commonly asked by our customers. Please contact us if you have a question about our process that is not answered below.
Why can a two-wire sensor remain detected as ON by 6ES7421-7DH00-0AB0 after the field output switches off?
For Siemens 6ES7421-7DH00-0AB0, compare the sensor residual current with the permitted quiescent-current limit and verify that the configured P-reading or M-reading reference matches the field circuit.
Why do long input cables produce unstable transitions when 6ES7421-7DH00-0AB0 is set to 0.5 ms?
The 0.5 ms setting on 6ES7421-7DH00-0AB0 is limited to a 100 m conductor run. Use a documented longer delay when the required cable length and process response permit it.
What should be checked when a replacement 6ES7421-7DH00-0AB0 reads the opposite field reference?
Confirm that Siemens 6ES7421-7DH00-0AB0 is configured for the same P-reading or M-reading mode as the removed module and that the field wiring follows that reference.
How can maintenance separate a field fault from an internal fault on 6ES7421-7DH00-0AB0?
On 6ES7421-7DH00-0AB0, EXTF identifies an external or field-side condition, INTF identifies an internal module condition, and the channel LEDs show the individual input states.
What must match before 6ES7421-7DH00-0AB0 is installed in an existing S7-400 station?
Verify the complete Siemens 6ES7421-7DH00-0AB0 order number, UC 24–60 V input requirement, 16-channel wiring, reading polarity, delay, and diagnostic parameters against the existing configuration.