Recovering from Serial Com File Transfer...with interruptions

[tomMcdonald]

I haven't had to do this in years....but am forced to work into a situation where I have to be able to send a file, via a serial connection (COM1 to another computer. I'm not to worried about making the connection to a com port, establishing a link, sending a file....my concern, which I thought of this morning at an hour I'm too embarrased to admit, is reliability.

I can see the possibility of this serial communcation line dropping the connection or the user doing something else (DOOM?) on the computer while waiting for a file transfer which causes a timeout or something else that is 'bad' for the serial connect...What is the recommended method for sending data via serial com channel and making sure everything is 'ok'...on a periodic basis?

If it's a big file, and the link goes down, what is the recommended, method of resuming with the first bit that was missed in the previous connection.

Assume the originating computer is a Microsoft computer. I don't know at this point, and I don't think it matters, what the receiving computer is...

thanks for any advice....

 

[Salem]

Is this an actual serial link to another machine, or is it via a modem to some remote machine?

If it's a big file, and the link goes down, what is the recommended, method of resuming with the first bit that was missed in the previous connection.

X-MODEM, Y-MODEM, Z-MODEM, KERMIT
All names of existing protocols used for sending data reliably over serial lines (including things like checksums, retransmission, auto-resume etc).
Things like Hyperterminal (standard with windows) can do some of those IIRC. You could probably find some library code around as well to do the same (if you're looking to write code for both ends).

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