40 kHz counting input for incremental encoder or 2-wire sensor
The 6ES7127-1BE00-0AB0 is a SIMATIC SC electronic submodule that provides one 40 kHz counting channel with a 24V DC counting input and a separate 24V DC directional input. Signal '1' is detected from +11 to +30V DC, drawing 6 mA typical at high level; signal '0' spans -3 to +5V DC, so the input thresholds are compatible with standard 24V PLC outputs and 2-wire proximity sensors. The module accepts a minimum pulse width of 12.5 µs, which together with the 40 kHz maximum counting frequency defines the edge resolution for high-speed incremental encoders or flow-meter pulse trains.
DIN-rail footprint and supply integration
At 10 mm wide and 51 mm deep, this submodule fits a single-width SIMATIC SC slot without stealing adjacent positions — critical when the backplane is dense with I/O and the cabinet depth is tight. Maximum cable length to the sensor is 100 m, which covers most machine-mount-to-panel runs; the 0.5 W power loss keeps the thermal load on the backplane negligible. Reverse polarity protection on the 24V DC supply is built in, so a swapped wire during commissioning won't damage the module.
2-wire sensor compatibility and quiescent current limit
The module explicitly supports 2-wire sensors, with a permissible quiescent current (off-state leakage) up to 1.5 mA — this means standard inductive proximity sensors with leakage below that threshold will not falsely trigger the counting input. No channel-to-channel isolation or diagnostics function is provided; the module is intended for simple single-channel counting where the backplane bus handles the data transfer.