The Siemens 6ES7401-2TA01-0AA0 is a SIMATIC S7-400 rack, type CR2, designed as the central rack for a redundant or segmented S7-400 system. It provides 18 slots arranged in 2 segments — one with 8 slots and the other with 10 slots — allowing you to partition the backplane into two independent P bus segments while keeping them in a single physical chassis. The P bus runs throughout both segments, meaning I/O modules in either segment communicate over the same backplane bus, but the segmentation lets you isolate power supply zones or separate control domains without a second rack. Two redundant power supplies can be plugged in, supporting high-availability configurations.
The rack measures 482.5 mm wide, 290 mm high, and 27.5 mm deep — standard 19-inch rack width, so it mounts in a 19-inch cabinet without adapters. The 290 mm height is roughly 6.5 rack units (1 U = 44.45 mm), so plan for 7 U of vertical space to allow airflow and cabling clearance above and below. Rated for 0 °C to 70 °C operating ambient, which covers most control-room and panel environments. The 70 °C ceiling is useful if the rack sits above a row of high-power drives or in a non-conditioned enclosure with solar gain.
No substitution needed — the 6ES7401-2TA01-0AA0 is the correct CR2 rack for new S7-400 builds or spares. If you are replacing a 6ES7400-1JA11-0AA1 (the 9-slot UR1 rack), note that the CR2 is wider (482.5 mm vs 257.5 mm) and has a different slot count and segmentation; it will not drop into the same panel footprint without mechanical rework.
Carries UL, CE, UKCA, FM, KC, EAC, and RCM approvals plus CCC (China Compulsory Certification). That covers installations in North America, the EU, UK, Russia/Eurasia, South Korea, Australia/New Zealand, and China — one rack for global machine builds.