When designing the VSPDL we have attempted to emulate the work of a standard serial port as closely as possible. All system calls supported by the serial port driver were carefully ported into the VSPDL and the behavior of the VSPs closely mimics that of "real" serial ports.
Shown above is a VSP block diagram:
| • | Serial interface presents an application interface, compatible with the standard serial port driver. LINUX applications are not able to tell the difference between a VSP and a "real" COM port. |
| • | TX and RX buffers are used to pass the data between the application and the DS. |
| • | Network interface communicates (through the TCP/IP network) with the target DS. The VSP transparently establishes and accepts data connections with/from the DS as needed. |
| • | On-the-fly logic (when enabled) is responsible for adjusting communications parameters of the serial port on the DS to the requirements of the application. For example, if the application wants the serial port to run at 19200 bps a special on-the-fly command will be sent to the DS telling it to change the serial port baudrate to 19200. Thus, the DS serial port functions just like the serial port and the PC! |
| • | Configuration file (vspd.conf) define different aspects of VSPDL operation. |