The Siemens 6ES7461-4AA01-0AA0 is a SIMATIC S7-400 interface module receiver IM 461-4, used for distributed coupling between racks in a distributed I/O configuration. It is a replacement part for the earlier variant, supporting cable runs up to 605 m between adjacent interface modules — covering long-distance rack-to-rack links without a C bus.
The module draws a maximum of 620 mA from the 5 V DC backplane bus, so the rack's power supply must have at least that headroom available for this slot. Power loss is rated at a maximum of 3 100 mW — heat dissipation that stays low enough for natural convection in a standard S7-400 rack, but check the overall thermal budget if the rack is densely populated. The 605 m maximum cable length between adjacent interface modules is the key deployment spec: it determines how far apart two racks can be placed in a distributed coupling setup. Plan the cable route to stay within that limit, including any service loops or vertical risers.