This is a Home Asistant Add-on that creates a Soft TCP-to-Serial bridge on your home Assistant server
Some Home Assistant (HASS) integrations connect with devices that natively use RS-232 serial ports, for example Russound RNET. Those integrations are written assuming that the controlled device (like Russound CAA66 or CAM6.6) will be connected via a TCP-to-serial adapter. This can be very convenient when the HASS controller and the device are on different racks or locations. In cases where the controlled device is right next to the Home Assistant server, it may not be practical to use an extra network port and a hardware TCP-to-Serial bridge (for example a Digi or Global Caché one). This Add-on repackages TCP2Ser, which is a software TCP to Serial bridge, and allows connecting a serial device to HASS using an inexpensive USB to RS232 adapter, based on the FTDI/Proliphix chipsets.
It is increasingly common to locate the HASS controller in a wiring/mechanical room somewhere in the basement of a home. Serially-connected devices (even Z-Wave/Zigbee radios) are then located at another place closer to the to-be serviced areas. A small HASS controller (like a Raspberry pi 4) with a USB to serial adapter can then be used to connect to the actual device. The same Raspberry Pi can also power and connect the Zigbee/Z-Wave Radios via the MQTT/Sockets addons that exist.