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Siemens 6ES7521-1BH00-0AB0 — Digital Input Modules

Siemens 6ES7521-1BH00-0AB0 Digital Input Module, 24 VDC, 32-

MPN6ES7521-1BH00-0AB0
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Siemens S7-1500 digital input module, 6ES7521-1BH00-0AB0, 24 VDC, with 32-bit counter, diagnostics, isochronous mode, and I&M data.

$144.78Ref. price · indicative, final on quote
Siemens 6ES7521-1BH00-0AB0 datasheet (PDF)
Sourced new & surplus through independent channelsAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

6ES7521-1BH00-0AB0 — Inputs
ParameterValue
Number of digital inputs16
2-wire sensor supportYes
6ES7521-1BH00-0AB0 — Electrical
ParameterValue
Rated value (DC)24 V
Input voltage at signal "1"+11 to +30V
Input voltage at signal "0"-30 to +5 V
Permissible range, lower limit (DC)19.2 V
Permissible range, upper limit (DC)28.8 V
Input current at signal "1" (typ.)2.5 mA
Power loss (typ.)2.6 W
Permissible quiescent current, 2-wire sensor, max.1.5 mA
Cable length, unshielded, max.600 m
Cable length, shielded, max.1 000 m
6ES7521-1BH00-0AB0 — Timing
ParameterValue
Input delay 0 to 1, min.0.05 ms
Input delay 1 to 0, min.0.05 ms
Input delay 0 to 1, max.20 ms
Input delay 1 to 0, max.20 ms
Input delay, parameterizable valuesYes
6ES7521-1BH00-0AB0 — Environmental
ParameterValue
Max. ambient temperature, horizontal installation60 °C
6ES7521-1BH00-0AB0 — Diagnostics & Isolation
ParameterValue
Diagnostics functionYes
Short-circuit (NAMUR sensor)No
Diagnostic alarmYes
Hardware interrupt supportYes
Isolation between channelsNo
Isolation between channels and backplane busYes
Isolation test voltage707 V DC (type test)
Channels per isolated group16
6ES7521-1BH00-0AB0 — Mechanical
ParameterValue
Depth129 mm
Height147 mm
Width35 mm

Product details

The Siemens 6ES7521-1BH00-0AB0 is a 24 VDC digital input module for the S7-1500 system, equipped with a 32-bit counter, gate start/stop, and diagnostic functions. Signal thresholds are -30 to +5 V for a '0' and +11 to +30 V for a '1', with a typical input current of 2.5 mA at signal '1'. Response times range from 0.05 ms to 20 ms depending on the transition direction.

Mounting and wiring note

Sized at 35 mm width, 129 mm depth, and 147 mm height; shielded cable reach is 1 000 m, unshielded 600 m. Wire-break detection triggers below 350 µA, and isochronous mode enables synchronized sampling.

Field service — fault isolation

Diagnostic alarms and hardware interrupts are available, signaled through a red ERROR LED and a green RUN LED. The firmware version is V2.2.0 and is field-upgradable. Module-specific interrupt (MSI) is supported, which can be mapped to the I&M data (I&M0 to I&M3) for asset tracking in large installations. The counting function uses a 32-bit width and can be parameterized online via prioritized startup.

Frequently asked questions

Can the 6ES7521-1BH00-0AB0 replace a 6ES7522-1BH01-0AB0 in a panel?

No. The 6ES7522-1BH01-0AB0 is a digital output module, while the 6ES7521-1BH00-0AB0 is a digital input module. They are not functionally equivalent and cannot be swapped without changing wiring, configuration, and possibly the power supply.

What does the 'DI' and 'MSI' ratings mean?

DI means digital input module (Yes, it accepts discrete field signals). MSI stands for module-specific interrupt (Yes, it supports hardware interrupts for event-driven processing).

MPN
6ES7521-1BH00-0AB0