VISA Find Resource Function Takes a Long Time to Execute

Issue Details

• When I use the VISA Find Resource function in LabVIEW™ it takes over 10 seconds to complete where before it would take less than a second. 
• Whenever I disconnect a real-time target from my PC or network, the VISA Find Resource is very slow to respond. How can I get around this?
• How can I prevent VISA Find Resources from searching for serial ports that are no longer present?

Solution

1. Delete any disconnected devices in NI MAX before running the LabVIEW code.
   • Refer to Remove Old VISA Resources from NI MAX and LabVIEW for instructions.
2. Reset the MAX Configuration Database before executing the VISA Find Resource function.
   • This can be done manually by following Reset and Fix the NI Measurement & Automation Explorer Database File.
   • Alternatively, the MAX Database can be reset programmatically by launching the ResetNIConfig.exe with the System Exec VI. Refer to How Can I Reset the MAX Database Without Opening NI MAX? for details on locating the executable.
3. Delete the VISA configuration file (visaconf.ini) and re-open NI MAX to force the generation of a new configuration file.
   • visaconf.ini is located in C:\ProgramData\National Instruments\NIvisa.
   • This option can be implemented programmatically by using the Delete Function to delete the file and the System Exec VI to re-launch NI MAX.
4. It may also be more suitable to use the System Configuration API to identify resources and hardware instead.
   • The Find Hardware VI returns a list of hardware connected to the specified system and it's execution time is not negatively effected by the presence of disconnected devices.
   • Note: the System Configuration VIs generally take longer to execute than the VISA Find Resource function.