AVSD is appointed for emulation of one, two or more (up to
200) serial streams. Hardware devices are not necessary. This product is
based on Windows XP DDK and doesn't require using devices of other
manufacturers. The whole product is created with the help of Microsoft tooling.
AVSD realizes full emulation of Serial Port functions,
connected with each other with the help of NULL-MODEM or full cable,
including DTR, CTS, DSR, RTS.
AVSD can be interesting for software (for Windows Platforms)
developers, who use external devices connected with computer by serial port.
Also, it will be interesting for developers of the products appointed for
connection of two or more computers through serial ports.

• Download Link 1