Data missing over modem with filetransfer. Using VISA stuff.

[Duvel]

I have a serial connection to the modem using VISA in Labview 6i.
I have a good connection with the other modem and then recieve a file. This file is good untill I go over 1000 - 1100 lines. From this point complete lines are missing. The total file is 6000 lines and 500kB of info.

- The VISA buffer is on max.
- I get no error message from Labview.
- Other prog like hyperterminal works fine.
- I tested 3 kinds of modems, same result.
- Serial speed = 115200, Modem connect at 33.6
- Hardware handshaking.

Q : Where is the data?
Q : Example of modem-connection?

[Dan_Mondrik]

Duvel:

What do you mean when you say "the VISA buffer is on max"? Have you called "VISA Set I/O Buffer Size", and if so, with what size? You should call this with the I/O input/receive buffer mask and with a size larger than what you expect to receive, such as maybe 600KB. Also, which version of Windows are you using? I have seen that call fail occasionally on Windows NT - be sure to check the output error cluster.

Also, what do you mean by saying that the modem connection is 33600 but the serial speed is 115200? I guess I don't understand the way the system is connected.

I know that our customers have successfully used NI-VISA with baud rates up to and including 230400, so this may be a more subtle bug.

If you continue to have this problem, I suggest sendi
ng an NI Spy capture log (if that doesn't make things magically work) and the actual text file being transferred, together in an email to NI tech support.

Dan Mondrik
Senior Software Engineer, NI-VISA
National Instruments

[Duvel]

Thanks for answer.

The Visa buffer is on 4294967295(changed it but no effect)
The mask on this is 16 (changed it but no effect)

I'm using it on Windows 2000 pro

The 2 modems I use are connected on same computer on different com-ports.

The meaning of this is that LabView sends over a file from one modem to the other and compares it. If the file is damaged by the transfer, the test is stopped and the data that's left in the DSP-Processor of the modem gets read-in into LabView, using a PCI-DIO-32HS. This part already works.

The modems connect over a PSTN and get a connection speed of 33.6
The modem to computer, the serial connection to modem is set to 115200.

[mikeeeee]

Hi, something questions related to this very old thread. So I can have one modem connected to the other modem over PSTN telephone line using normal Windows dial program? Then after that, both PCs can communicate to each other just as if they are linked by serial ports? That means, if 1 PC writes some data to the serial port where the modem is connected, the data will automatically be transferred through PSTN telephone line and goes through the other modem and reach the other PC's serial port?

Thanks in advance.

[Dennis_Knutson]

duplicate post