The 6ES7321-1BL00-0AA0 is a SIMATIC S7-300 SM 321 digital input module offering 32 isolated inputs rated at 24 V DC, terminated through a single 40-pin front connector. It accepts 2-wire proximity sensors and provides optocoupler isolation between the channels and the backplane bus. The module occupies a standard 40 mm wide slot and draws 15 mA from the 5 V backplane supply plus 6.5 W from the 24 V load circuit.
Input characteristics and wiring
Each input channel has a nominal input current of 7 mA at 24 V DC. The signal "1" threshold is 13 to 30 V, signal "0" is -30 to +5 V. Input filtering is fixed: the transition from 0 to 1 or 1 to 0 takes between 1.2 ms and 4.8 ms, with no parameterization available. The module supports 2-wire sensors with a permissible quiescent current up to 1.5 mA. The 32 inputs are electrically isolated from the backplane bus via optocouplers, and the channel groups are isolated from each other in groups of 16. The module does not provide diagnostics, alarms, or hardware interrupts.
Temperature derating and cable lengths
The module can drive all 32 inputs simultaneously up to 40 °C ambient. Above that, derating applies: at 60 °C only 16 inputs may be active. Unshielded cable runs up to 600 m are permitted; shielded runs up to 1 000 m.