usb-485/4 baudrate

[ilariaIn]

Hi All, 

 I'm using a NI-485/4 interface, but I can't set a baudrate greater than 115200 (error -1073807330 in visa serial configuration). Datasheet says USB-485 maximum baudrate is 460.8 kbps. What can I do?

Thank you

[ZYOng]

Error -1073807330 on VISA Configure Serial Port

The error might not be due to the baud rate. Can you set the baud rate without any errors if other settings remain the same?

[ilariaIn]

Hi, thank you for the reply. Error is definitely the baudrate because if I use another baudrate (under 115200) it works. I don't understand why I can't use 128000 kbps even if my device (https://www.ni.com/it-it/shop/model/usb-485-4.html?partNumber=778476-14) can work up to 460.8 kbps.

Am I doing something wrong?

Thanks

[GerdW]

Hi ilarialn,

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@ilariaIn wrote:

I don't understand why I can't use 128000 kbps even if my device … can work up to 460.8 kbps.

Am I doing something wrong?

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115.2kBaud and 460.8kBaud are "common" baudrates, they also differ by an integer factor of 4. Your device will(should support them as written in the datasheet.

You are asking for an "uncommon" baudrate of 128kBaud: why do you need that uncommon speed?

I think your device tells you with that error message it does not support this uncommon baudrate as it (most probably) derives its baudrates using a fixed oscillator and a frequency divider using integer ratios. That's why 460.8/115.2/56.6/28.8/14.4 kBaud are supported, but not your 128kBaud…