serial baudrate

[Jackson_Peacock]

hi,

I have an application that needs to communicate at 76800 baud. (The device I am communicating with only supports the standard baudrates of 2^n*300). When I passed 76800 to OpenComConfig, it did not return an error, however it appear to have opened the port at 19200 baud, not 76800.

I have used the port at 19200, and 38400 with no problems. I am using LabWindows/CVI 5.5 and Windows 2000.

[DiegoF]

Hi,

The limitation on the baud rate option is at the hardware level. Check this knowledge base article, which describes how the allowed baud rates for NI hardware is calculated, but it applies to any serial hardware: Which Baud Rates Do the National Instruments Serial Boards Support?

DiegoF
National Instruments

[K_seeker]

Jackson,

What brand of RS232 card you are using that is capable of cummunicating at 76.8Kbaud. I have a project that needs this setting. I would appreciate if you can let me know if you were able to find a hardware that was able to work at this baud rate. I am looking for one in CPCI version to go into NI PXI chassis.

Thanks

[mvr]

Would the NI PXI-8430/2 work for your application?

https://www.ni.com/en-us/support/model.pxi-8430-2.html

Message Edited by mvr on 03-20-2007 08:01 AM

[K_seeker]

Yes, I beleive so. Do you know for sure it will work at that Baud Rate. Thanks.

[mvr]

The NI documentation is a little cryptic but it states:

"All NI serial hardware supports the standard baud rates. In addition, the PCI/PXI-843x family of hardware supports any baud rate between 2 bit/s and the maximum supported baud rate for that interface."

The maximum baud rate is 1000Kbits/s.  They do not specify the resolution specifically but it was listed in the data sheet as at least as good as 1% which is well beyond the 3-5% required by a typical application.  Unless you have a really extreme timing accuracy requirement (like testing a serial port at the timing boundry conditions) it should easily support the baud rate you specified.  You may want to call or email your NI sales rep or app engineer to verify the details.

[K_seeker]

Thanks mvr.

I waiting for just that. I noticed the same text on the manual and waiting for NI to confirm that I can use it for 76.8Kbaud. I wish to know for sure before I buy the hardware.