What this module fits
The Siemens 6ES7321-1BP00-0AA0 is a SIMATIC S7-300 digital input module packing 64 channels in a 40 mm wide housing. It is isolated in groups of 16, meaning each group of 16 inputs shares a common reference. This module lacks any on-board diagnostics, parameterization, or interrupt capabilities—it's a straight 24 VDC sink/source input block. This module requires a dedicated front connector cable and terminal blocks for termination.
Signal characteristics and power draw
The module operates on a 24 VDC supply with typical power loss of 7 W. Input thresholds are -30 to +5 V for a logical 0 and 13 to 30 V for a logical 1, drawing a typical 4.2 mA per channel at signal 1. Switching delays run 1.2 ms minimum to 4.8 ms maximum for both 0-to-1 and 1-to-0 transitions. Unshielded cable runs up to 600 m and shielded up to 1 000 m are supported. The backplane bus draws up to 100 mA at 5 V DC; isolation between channels and backplane is via optocoupler, tested at 500 V DC.