Product : ISaGRAF IDK V3 - Source files for MS-DOS
Date : 10-December-1997
File : DOSnet.communicating with DOS Target through Ethernet.htm
Subject : HOW TO COMMUNICATE with DOS TARGET through ETHERNET
Keywords: Communication - Ethernet - DOS target
HOW TO COMMUNICATE with DOS TARGET through an ETHERNET LINK ?
The ISaGRAF DOS target standard communication part is implemented for serial link only. This is because DOS is a monotasking OS while TCP/IP is mostly implemented through blocking sockets.
Communicating to the DOS target through an Ethernet link is fully possible but requires some code implementation according to the following scheme.
- A TCP/IP non blocking stack is needed to be implemented as a DOS driver (for exemple resident to the DOS system)
- On the target side, the kernel will use this driver as if it were a serial link, this whatever is the real hardware behind (Serial link, Ethernet board).
It means testing if there is a character, read characters, write characters.
- Other adapting points will have to be taken into account like for example adapting TCP/IP frames (255 cars with no CRC) to serial like frames (variable length with CRC)
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