Siemens 6ES7521-1BH50-0AA0 SIMATIC S7-1500 DI 16x24VDC SRC BA Digital Input PLC I/O Module

The Siemens 6ES7521-1BH50-0AA0 is a SIMATIC S7-1500 digital input module, DI 16x24VDC SRC BA, providing 16 sourcing-type 24 V DC inputs wired in a single group of 16. It follows the IEC 61131 input characteristic curve type 3 with an input delay of 3 to 4 ms, and it needs a front connector (screw terminals or push-in) ordered separately.

Technical Specifications

Selection Notes

BA in the product designation marks the Basic performance class within the S7-1500 digital input family, so it covers standard-accuracy 24 V DC sensing without the tighter delay classes or diagnostic reporting of the HF (high-feature) modules in the same slot count. The sourcing (SRC) wiring means field sensors switch the positive rail into the input, matching PNP-type proximity switches and sensors already common on 24 V DC panels; sinking-type NPN sensors need the sinking variant instead. Because all 16 channels share one input group, this module suits applications that do not need per-channel potential separation; where individually isolated input groups are required, a module with smaller group sizes is the better fit.

Applications

Panel-mounted status and limit-switch sensing on machines already wired with PNP-type 24 V DC field devices, where the standard 3 to 4 ms input delay is fast enough for the application.