For secure serial data transmission. The Secure Device Server SN3401P is an external IP-based network device that securely connects older serial RS-232/422/485 devices to an Ethernet network and enables remote access from any computer. The SN3401P is particularly suitable for industrial process control applications, as Supervisory Control and Data Acquisition (SCADA) systems for collecting data from PLCs, measuring devices, and sensors via serial interfaces are widely used in many industries. The SN3401P translates data bidirectionally between serial and Ethernet formats, allowing access to data from all data acquisition devices from local and remote locations over an Ethernet network. The SN3401P features a range of useful operating modes. It supports secure TCP server/client, secure serial tunneling server/client, secure Real-COM, and console management modes for security-critical applications such as telecommunications, access control, and remote site management. Additionally, the IEEE 802.3af-compatible models can be powered by a PoE-PSE device without the need for an additional power supply.