Siemens 6ES7521-1BL00-0AB0 Digital Input Module, 24 V DC
Siemens SIMATIC S7-1500 digital input module, 6ES7521-1BL00-0AB0, 24 V DC P-reading, 32-bit counter, MSI, current lifecycle.
Specifications
| Parameter | Value |
|---|---|
| Number of digital inputs | 32 |
| 2-wire sensor support | Yes |
| Parameter | Value |
|---|---|
| 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.) | 4.2 W |
| Permissible quiescent current, 2-wire sensor, max. | 1.5 mA |
| Cable length, unshielded, max. | 600 m |
| Cable length, shielded, max. | 1 000 m |
| Parameter | Value |
|---|---|
| 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 values | Yes |
| Parameter | Value |
|---|---|
| Max. ambient temperature, horizontal installation | 60 °C |
| Parameter | Value |
|---|---|
| Diagnostics function | Yes |
| Short-circuit (NAMUR sensor) | No |
| Diagnostic alarm | Yes |
| Hardware interrupt support | Yes |
| Isolation between channels | Yes |
| Isolation between channels and backplane bus | Yes |
| Isolation test voltage | 707 V DC (type test) |
| Channels per isolated group | 16 |
| Parameter | Value |
|---|---|
| Depth | 129 mm |
| Height | 147 mm |
| Width | 35 mm |
Product details
Frequently asked questions
Can 6ES7521-1BL00-0AB0 be used as a counter?
Yes. The module has a 32-bit counter function that can be parameterized, with gate start/stop and isochronous mode support.
24 V DC input module with integrated counter
The Siemens 6ES7521-1BL00-0AB0 is a digital input module for the SIMATIC S7-1500 system, supporting 24 V DC P-reading inputs that can be used as a 32-bit counter. It also provides MSI (Motion Sensor Interface) capability, meaning it can directly connect to incremental encoders or proximity sensors that output A/B signals, reducing the need for a separate counting module.
Signal thresholds and wiring length
Signal '0' is detected from -30 to +5 V, signal '1' from +11 to +30 V with a typical input current of 2.5 mA at 24 V. Unshielded cable runs up to 600 m; shielded runs up to 1000 m, which covers most panel-to-field distances in a typical plant. The module supports wire-break detection for input currents below 350 µA, so a broken field wire is flagged as a diagnostic alarm rather than a false '0'.