Siemens 6ES7521-1BH00-0AB0 SIMATIC S7-1500 DI 16x24VDC HF Digital Input Module

The Siemens 6ES7521-1BH00-0AB0 is a SIMATIC S7-1500 DI 16x24VDC HF digital input module with 16 channels in one group, 2 of which can run as counters up to 6 kHz. Input delay is parameterizable from 0.05 to 20 ms per IEC 61131 type 3. It draws up to 20 mA from a 24 V DC supply and reports wire-break and short-circuit diagnostics.

Technical Specifications

Selection Notes

At 16 channels the DI 16x24VDC HF is the lower-density counterpart to the DI 32x24VDC HF in the same 35 mm housing footprint — pick this one when the input count for a segment is under 16 and rack space is not the constraint, since the per-channel cost is otherwise similar. Two of the 16 channels double as 32-bit up-counters to 6 kHz, useful for basic flow or pulse counting without a dedicated high-speed counter module. Wire-break detection to below 350 µA flags an open field circuit at the module level, useful for safety-adjacent digital inputs like guard switches even though this module itself is not fail-safe rated.

Applications

Fits S7-1500 stations needing moderate digital input counts with basic pulse-counting capability — machine interlocks, sensor banks, and general discrete field wiring.