What this CP 343-1 LEAN does in the rack
The Siemens 6ES7343-1CX10-0XE0 is a CP 343-1 LEAN communication processor that slots into an S7-300 rack to provide Industrial Ethernet connectivity — it handles the TCP/IP and ISO-on-TCP stack so the CPU can focus on logic.
Lifecycle status — EOL hot, sourcing reality
Replacement path for the S7-300 Ethernet slot
Siemens has moved the S7-300 Ethernet portfolio to the CP 343-1 Advanced series (e.g., 6GK7343-1EX30-0XE0) for higher performance and more protocol support. The LEAN variant lacks the Advanced's additional features like PROFINET IO controller capability and integrated two-port switch. If the application only needs basic TCP/IP connectivity for an S7-300, the LEAN was the cost-optimized choice; the Advanced adds functionality but also a different order code and firmware baseline.