I am planning to use the Arduino as a replacement for a USB-Controlled Digital I/O device, which will be integrated into an existing C++ software package that I created. I understand that the Arduino acts like a Serial device to a PC. Every serial device can be controlled by its own set of commands and queries. However, the only commands and queries that I've found for the Arduino involve flashing one-time programming to it from the "inside" rather than providing real-time automated control from the "outside."
Can anyone tell me where can I find the complete list of Arduino serial command & query strings? Thanks.