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adjusting serial communication baud rate

Hi all,

What is the maximum baud rate that I can use for serial communication. LV shows that the max. rate is 9600. I want a baud rate of 57,600. Is it possible to perform read and write operations using serial vi's at 57,600 or higher baud rates? thanks for any suggestions and inputs.
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I haven't gone higher than 57,600 but if your serial port and device support it, there shouldn't be a problem. Why do you think that LabVIEW shows a maximum rate of 9600? On all of my versions of LabVIEW and with both VISA and traditional serial, the baud rate is a U32 that you can enter any number you want.
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Hi Dennis,

My LV Front panel shows a U32 too for entering a specific baud rate. But I was not sure if my serial communication VI's will work if I specify a baud rate higher than 9600. I always thought that the maximum rate at which my serial port can communicate with any instrument is 9600 baud. However, I have an instrument which sends data at 57,600 baud rate to my PC. Can I pick up data at this baud rate using simple serial VI's? Is there any documentation that talks in detail about baud rate functions with serial communication VI? Also, I am not using the Visa Serial functions. I am using the simple serial port init. vi and serial port read. vi and serial port write. vi, Thanks again for the quick response.
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If you can talk to the instrument using something like hyperterminal, then you should have no problem using LabVIEW. It's all the same hardware inside the pc.
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kmoorthy76107 writes:

> Hi Dennis,
>
> My LV Front panel shows a U32 too for entering a specific baud rate.
> But I was not sure if my serial communication VI's will work if I
> specify a baud rate higher than 9600.

That's a reasonable limit to work without hardware handshaking.

> I always thought that the maximum rate at which my serial port can
> communicate with any instrument is 9600 baud. However, I have an
> instrument which sends data at 57,600 baud rate to my PC. Can I pick
> up data at this baud rate using simple serial VI's? Is there any
> documentation that talks in detail about baud rate functions with
> serial communication VI? Also, I am not using the Visa Serial
> functions. I am using the simple serial port
init. vi and serial
> port read. vi and serial port write. vi, Thanks again for the quick
> response.

You'll have to use the correct hardware handshaking mode at
communication setup on a FIFO buffered UART. But that's standard since
the days of Pentium 1 CPU's and motherboards.

Johannes Nie?
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hi kmoorthy,

test your COM - line with attached vi
bmp - file shows timing for different baudrates

regards
wha
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I also have experienced problems at baud rates above 9600.  I have a communications VI that works fine at 9600 or below, but when I change the baud rate value to anything above 9600 I get an error when labview tries to initialize the serial port.   I seem to remember reading something earlier about 9600 being a limitation of the labview serial drivers, (not a limitation of the hardware).   Has anyone out there really successfully used labview to communicate with a device at baud rates higher than 9600? Thank you.

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There is no limitation to the serial drivers that I know of. I use them at 115K. If you get an error, you should provide the error number so someone knows what you are talking about and maybe provide a solution.
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Are you using the LabVIEW PDA module? As discussed in this thread...
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I was able to get the serial communications running at 57,600 baud using a real PDA.   The error I previously got when initializing the port was -1073807343.  I traced this to the WCESCOMM.EXE process.  (I develop on the PC and then export to the PDA).   This process is used with ActiveSync which is usually running in a PDA developement environment.  If this process is active or sleeping, it may tie up the port and cause serial communications to fail.  The fix is to kill this process when trying to use Labview to access the Serial Port.   It will restart when you attempt to connect the PDA, so it doesn't hurt anything, but Labview will not function correctly out the serial port if it is running.

 

 

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