Solution
Software or serial flow control is a way to pause and restart the transmission of serial data to ensure all data is sent and received correctly. There are several different versions of which can be found here:
Serial Settings:Flow Control. Normally, all the developer has to do is configure the
VISA Configure Serial Port VI in LabVIEW and ensure their UUT supports this method of serial communication.
The issue is down to the difference between
Revision C (
198106C-11L) and
Revision D (
198106D-11L) of the PCIe-8430/16. To determine the model revision, check the part number - information on how to find it is here:
Finding the Serial Number of My NI Product .
For
Revision C of the PCIe-8430/16, flow control works and has the expected behaviour where the XON/OFF commands are not read into LabVIEW. However, with
Revision D, the XON/OFF commands are often read into LabVIEW, especially if the commands are sent to close to each other. Unfortunately, this is now the expected behaviour as there was a component change between Revision C and Revision D, from the Xilinx Spartan6 to a Oxford UART.
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Work Arounds:
- Implement LabVIEW code that deletes XON/XOFF from the incoming string from the VISA Read. Using the function Match Pattern and Concatenate Strings can help.
- Example code to search and delete characters from a string:
Note: This image is a LabVIEW snippet, which includes LabVIEW code that you can reuse in your project. To use a snippet, right-click the image, save it to your computer, and drag the file onto your LabVIEW diagram.
- Try to source older PCIe-8430/16 with the part number 198106C-11L from 3rd party vendors.