Siemens 6ES7 431-1KF20-0AB0
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Siemens 6ES7 421-1BL00-0AA0 is an SM 421 digital input module from the SIMATIC S7-400 family. It is used when an existing S7-400 station must acquire 24-V-DC digital signals from switches, limit positions, sensors or 2-wire proximity sensors. The Siemens reference manual identifies this version as DI 32 x 24 VDC with 32 inputs arranged in one isolated group. This makes clear that Siemens 6ES7 421-1BL00-0AA0 is a 32-channel input module for process signals rather than a CPU, power supply or digital output module. The module uses a 24-V-DC electronics supply, includes reverse-polarity protection and permits all 32 inputs to be activated simultaneously according to the manual. For wiring, maximum cable lengths of 600 m unshielded and 1000 m shielded are relevant. The input characteristics specify 11 to 30 V for signal 1, -3 to 5 V for signal 0, and input current of 6 to 8 mA at signal 1. Further documented data include an input delay of 1.2 to 4.8 ms, a green status LED for each channel, typical power dissipation of 6 W and dimensions of 25 x 290 x 210 mm. The 32-channel configuration, 24 V DC signal level, IEC-61131 Type 2 input characteristic and permissible cable length are decisive when selecting a replacement. These details distinguish Siemens 6ES7 421-1BL00-0AA0 from other S7-400 digital modules and later replacement versions without claiming universal interchangeability. For retrofit, troubleshooting and spare-parts stocking, compare the input count, signal level, wiring method and module width with the installed drawings, parts lists and STEP-7 hardware configuration.
| Manufacturer | Siemens |
|---|---|
| Product series | SIMATIC S7-400 / SM 421 |
| Manufacturer/Order/Identification number | 6ES7 421-1BL00-0AA0 |
| Device type | SM 421 digital input module |
| Inputs | 32 digital inputs |
| Rated voltage | 24 V DC |
| Signal 1 | 11 V to 30 V |
| Signal 0 | -3 V to 5 V |
| Input current | 6 mA to 8 mA at signal 1 |
| Input delay | 1.2 ms to 4.8 ms for 0 to 1 and 1 to 0 |
| Sensor type | Switches and 2-wire proximity sensors conforming to IEC 61131 Type 2 |
| Cable length | Max. 600 m unshielded, max. 1000 m shielded |
| Electrical isolation | Between channels and backplane bus; not between individual channels |
| Current consumption | Max. 30 mA from the backplane bus and max. 30 mA from L+ |
| Power dissipation | Typically 6 W |
| Status indication | Green LED for each channel |
| Dimensions | 25 x 290 x 210 mm |
| Weight | Approx. 600 g |
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The module is designed for 24 V DC digital input signals and, according to Siemens, is suitable for switches and 2-wire proximity sensors conforming to IEC 61131 Type 2.
Siemens describes this version as DI 32 x 24 VDC with 32 digital inputs in one isolated group.
Yes, we provide a 14-day functional guarantee for used items. This means the component must be operational when received.
Please note that the guarantee only applies when the warranty seal is undamaged.
If a defect occurs within 14 calendar days, please contact us in writing. Subject to availability, we will provide a replacement or refund the full purchase price after return.
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