Central rack for S7-400 CPU and I/O
The Siemens 6ES7401-1DA01-0AA0 is the CR3 central rack for the SIMATIC S7-400 system, providing 4 slots for the CPU and I/O modules in a single backplane assembly. It includes the P bus, which is the parallel backplane bus that carries I/O data between the CPU and the modules — without it, the rack cannot communicate with the inserted cards.
Slot count and physical fit
With 4 slots, this rack is sized for a single CPU plus up to three I/O or interface modules in a compact central configuration. The CR3 is a central rack, meaning it holds the CPU; it is not an expansion (ER) rack. Dimensions are 130 mm wide, 290 mm high, and 27.5 mm deep. Operating temperature range is 0 °C to 70 °C, covering most conditioned industrial enclosures but not extended-range applications like outdoor cabinets without climate control.
The 6ES7401-1DA01-0AA0 carries a broad set of global approvals: CE, UKCA, UL, FM, KC, CCC, EAC, and RCM — covering installations in North America, Europe, Asia, and the EAEU customs union.