How do i clear the receiver and send buffer?

[unkayged]

I am trying to communicate with the Votsch 3050 thermal chamber, with LabVIEW as the control software via serial RS232. In sending the required ASCII strings, there was no response from the chamber, yet no error.

The manufacturers indicate clearing the receive and send buffer using the the "PurgeComm(HANDLE hFile, DWORD dwFlags)" function in C, but offer no LabVIEW support.

Does any one have any ideas on how i can do this using LabVIEW? Any Information or VIs would be greatly appreciated.

[wha@atmel]

Hi,

find typically in C:\Program Files\National Instruments\LabVIEW 6x\vi.lib\platform\_sersup.llb
Here you have "windows Flush com buffers.vi".

Helpful ? Independent of that, I have sent you already on 14.03.2002 a .llb for VT4004 - thermal chamber. I wonder about the fact, that you gave no comment/answer - this should be very common to your oven.

regards
wha

[unkayged]

Sorry for the late reply and comment. It did not work,Anything i send returns a zero error, yet no return string at all. So i ended up contacting Weiss Teknikal. They asked for the clearing of the buffer.

I'll try that and let you know. Your help is very much appreciated

[Randy Solomonson]

VISA also has a "VISA Flush I/O Buffer" command.

Randy Solomonson
Application Engineer
National Instruments

[dsbuxi]

Hello!

I have the same problem.

I have used both Flush I/O and clear, and each time i do not get a string back.

I would be grateful for any replies! Thanks!

[Dennis_Knutson]

In order for serial communciation to work, you have to have the correct cable (null modem or strait-through), com settings correct (baud rate, parity, handshaking, etc.) and for instruments that require it, send a valid command properly terminated. Before you even attempt to write your own program, you should first try talking to it with a terminal emulator program such as Hyperterminal. Once that works, you know you've got the first two correct. If you've got it to work with Hyperterminal and can't get your program to read anything, then a very typical problem that beginners have with RS-232 and LabVIEW, is not sending a termination character with the write string. This is usually a CR or LF character (your manual should tell you which one). Add it using the concantanate string and the constants on the string palette or turn on '\' Display Codes on your string control and add a \n or \r to your command.

[dsbuxi]

Dear Dennis!

Thanks for your reply!

I successfully used a hyperterminal programm (Hterm) to check the communication settings. That was not a problem.
The message send to the appliance ends with a checksum string. Is the character termination \n or \r that you suggested a part of this?

I did try running the programm with \n or \r but did not seem to work =(.

I have a patient monitor that is supposed to deliver blood pressure readings to the LABview program. On increasing the blood pressure (using a step function) i notice a delay in response in the hyperterminal program as well.

Can this be solved in LABview?

[Dennis_Knutson]

I've never had a problem using LabVIEW when Hyperterminal worked so it shouldn't be an issue. The termination character would be separate from the checksum. When you use Hyperterminal, I assume you send a command with checksum and then hit the enter key? Hyperterminal automatically appends a CR/LF so usually, all you have to do is add that to your program. Are you using one of the example programs that ship with LabVIEW or have you written your own? If you've written your own, can you attach the program? What is the instrument and can you attach an electronic copy of the manual or give a link to it?

[sonjajs]

Hi, I am trying to communicate with Vötsch 7060 and have the same problem with hyperterminal.

How could I send msg through hyperterminal to the champer?

I have set bautrate, and typed $01I<CR> as the introduction, but got no response from the champer.

Is there anything wrong?

 

[Coq_Rouge]

 @dsbuxi I have worked with many patient monitors. They often work in a client server setup. Data is not sent before you request it. And the communication has to follow a certain protocol. Your job will be to implement this protocol in Labview.  This is not too hard, but it requires some reading to understand the protocol. I am not able to send you any code, but feel free to ask if you need some help regarding the protocol 

And you may have to order or make a custom cable. But you will also find this information in the protocol description. Good luck

Message Edited by t06afre on 01-07-2009 09:03 PM