What the CP 443-1 Basic does in an S7-400 rack
The Siemens 6GK7443-1BX01-0XE0 is a CP 443-1 Basic communication processor that handles Industrial Ethernet connectivity, offloading protocol stack processing from the CPU.
No official successor or replacement order code is recorded for this part — it is the current offering for basic Ethernet communication in the family.
Compatibility and fit for S7-400
The CP 443-1 Basic plugs into any free slot and communicates with the CPU over the P-bus without consuming additional I/O addresses. For a line-down replacement or a new build, confirm the S7-400 CPU firmware version supports the CP 443-1 Basic — Siemens compatibility matrices list the minimum STEP 7 version and CPU firmware level.