What this module is
The Siemens 6AG1226-6BA32-5XB0 is the SIPLUS variant of the SIMATIC S7-1200 SM 1226 F-DI 16×24 V DC fail-safe digital input module, built on the 6ES7226-6BA32-0XB0 with conformal coating added for corrosive and condensing atmospheres. It drops onto the S7-1200 backplane beside the F-CPU as a PROFIsafe slave and contributes 16 fail-safe inputs that the safety program reads as either 16 single-channel (1oo1) signals or 8 dual-channel (1oo2) pairs — each pair of inputs a.x and b.x is independently assignable.
Signal levels and input filter
Signal "0" is recognised from -30 V DC to +5 V DC, signal "1" from 15 V DC to 30 V DC, with a typical 5 mA input current at the "1" level and a maximum quiescent current of 0.5 mA still tolerated as "0" — a comfortable margin against sensor leakage on long home runs. The input filter is parameterisable in five steps: 0.8 / 1.6 / 3.2 / 6.4 / 12.8 ms, so the integrator trades noise immunity against response time per channel. Cable-length guidance is conditional on the filter step and the 0.8 ms input-delay setting: shielded cable up to 200 m is supported at 0.8 ms to 12.6 ms input filter, and the same 200 m ceiling applies unshielded at 0.8 ms to 12.6 s — with the explicit caveat that an input delay of 0.8 ms forces shielded cable on the digital inputs and the sensor supply.
Channel-count derating vs temperature
All 16 inputs are usable up to 40 °C, after which Siemens specifies 16 inputs at 45 °C vertical mounting and 16 inputs at 55 °C horizontal mounting — so channel count does not drop with temperature on this variant, but orientation does become the governing detail once the cabinet runs warm. The operating envelope is -40 °C to 70 °C with a permissible change rate of 5 °C to 55 °C at 3 °C per minute, and installation altitude is limited to 2 000 m above sea level.
Power and bus draw
The module draws 155 mA from the backplane 5 V DC (SM bus) and takes its load-side supply from L+ at 24 V DC nominal, with a permissible range of 20.4 V to 28.8 V DC and a quiescent draw of 130 mA from L+ before sensor current is added. Sensor load scales linearly with usage: each input that is actually wired adds 6 mA to the L+ budget, plus whatever Vs1 / Vs2 current is drawn downstream — plan the stack headroom accordingly. Power dissipation is typically 7 W, which matters for cabinet thermal sizing on a fully loaded F-CPU + F-DI stack.
Harsh-environment posture (the SIPLUS reason)
Mechanical footprint is 70 mm wide × 100 mm tall × 75 mm deep, which fixes its slot allocation on the S7-1200 DIN rail and its thermal footprint inside the enclosure.
Lifecycle status is current, so the 6AG1226-6BA32-5XB0 fits new-build safety I/O budgets rather than a phase-out buy.