What it is and where it fits
The Siemens 6GK7343-1GX21-0XE0 is a CP 343-1 Advanced communications processor that connects an S7-300 PLC to Industrial Ethernet at 10/100 Mbit/s via a single RJ45 port. It mounts on the S7-300 rail and occupies a double-width slot, measuring 80 mm wide by 125 mm high by 120 mm deep. Powered by 24 V DC through a 2-pole pluggable terminal block, the module dissipates 14.7 W and is rated IP20 for use inside a control cabinet.
Key protocol and service support
The processor supports DCP (Discovery and Configuration Protocol) for device identification and parameter assignment on PROFINET networks, NTP for time synchronization across the plant, and LLDP for automatic topology discovery. TCP/IP and SNMP v1 are available for standard network integration, and the module includes ACL (IP-based access control list) for restricting communication to trusted stations. A C-PLUG slot lets you store the configuration on a removable medium, so a replacement module can be swapped in without re-commissioning.
Memory and data handling
The module provides 30 Mibyte of RAM for data buffering and 28 Mibyte of flash file system for storing FTP files, email attachments, or web pages. It can act as an FTP client (up to 10 simultaneous connections) and as an FTP server (up to 2 connections), and supports email client functionality with one maximum connection.