What this pulse module handles on the mill floor
The Siemens 6ES7138-6EB00-0BA0 is a TM Pulse 2x24V module for the ET 200SP distributed I/O system, handling two 24 V DC pulse outputs with integrated encoder counting. It maps 32 bytes of input and 16 bytes of output onto the backplane, so a single slice can drive two PTO axes or count two incremental encoders while the CPU reads position and status in one cycle. Rated 24 V DC with a typical power loss of 1.5 W, it keeps the thermal budget tight in a crowded DIN-rail row — no forced cooling needed unless the enclosure ambient exceeds 60 °C.
Signal timing and cable reach that matter for a strip mill
The module accepts pulse trains up to 200 kHz on shielded cable, with max cable length 50 m at that frequency; at 10 kHz and below it runs the full 600 m shielded or unshielded. Input filter is parameterizable from none up to 20 ms in eight steps. The minimum signal edge time is 6 µs when filtering is set to none — fast enough to catch a 200 kHz quadrature edge without missing counts. Signal thresholds are -5 to +5 V for logic 0 and +11 to +30 V for logic 1, with a typical current draw of 2.5 mA at 24 V. That 11 V low-end threshold gives noise immunity against coupled drive EMI — the module won't false-trigger on ripple from a nearby VFD.
Panel fit and wiring constraints
Dimensions are 15 mm wide, 73 mm high, 58 mm deep — it occupies one ET 200SP slice position. The 15 mm width leaves room for a 32-channel DI next to it in the same 200 mm DIN rail section. Supports I&M data (I&M0 to I&M3), diagnostic alarm, isochronous mode, and automatic encoding of the BaseUnit. Compatible with S7-300, S7-400, S7-1200, and S7-1500 via the control and feedback interface.