File transfer over RS232

[Sue Campbell]

I want to transfer a complete file from one PC to another, using mobile phones connected to each. The connection for this test is RS232. I've tried using XModem in Labwindows/CVI but this transfer the data and not the file as a whole. The development environment can be either Labwindows/CVI or Visual C++ 6.0

[Jeremiah Cox]

Hello Sue,
I assume that you are using some cellular phone modems that provide the RS-232 interface. The benefit to using one of these newer modems is that they have built in data compression and error correction to speed up and protect our data transfers. Your statement that Xmodem "transfer the data and not the file as a whole" is confusing. The XModemSend() and XModemReceive() functions are designed to transfer a whole file over a serial connection. Possibly you are trying to send a very large file (Megabytes) over the modems and the connection rate is very slow (2 kilobytes/s)? If this is the case, then the probability that a timeout or error may occur during the file transfer are increased significantly -- try increasing the wait period and maximum number o
f retries in XModemConfig(). If this is not the case, then please provide us with further details and clarification so that we can offer additional advice.

Jeremiah Cox
Applications Engineer
National Instruments
http://www.ni.com/ask