DOSNET.HOW TO COMMUNICATE with DOS TARGET through ETHERNET

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

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Question:

HOW TO COMMUNICATE with DOS TARGET through an ETHERNET LINK ?

Answer:

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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