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Why Don’t My Ports Appear Under VISA Resources in MAX?

Primary Software: Driver Software>>NI-VISA
Primary Software Version: 2.5
Primary Software Fixed Version: N/A
Secondary Software: N/A
Hardware: Serial>>RS-232>>PCI-232I/2

Problem:
I have 6 available COM ports on my computer. These ports are displayed in Device Manager in Windows, but I cannot find them in Measurement & Automation Explorer (MAX). Additionally, when I try to use the VISA Find Resource VI in LabVIEW with the "?*" (find all resources) expression, the ports are not found, and error -1073807202 is returned.

Solution:
This kind of behavior is typically encountered when the NI-VISA driver has not been properly installed. The NI-VISA driver is located on the device driver CD which is shipped with LabVIEW. Sometimes people forget or choose not to install the device driver CD when installing LabVIEW. There are two ways to determine if the NI-VISA driver is installed on the computer.
  1. Check for the driver in MAX. Look in My System>>Software. If the driver is installed on the computer it should be displayed here as NI-VISA.

  2. Another way to check for the presence of the driver on the system is to look for the visa32.dll file. When the driver is installed visa32.dll is placed by default in C:\WINDOWS\System32\
If you verify that the driver is not installed, you can install it from the device driver CD that shipped with LabVIEW. After installing the driver, the ports should now appear in MAX and be listed among the available VISA resources in LabVIEW.

Related Links:
Drivers and Updates: Current NI-VISA Versions
KnowledgeBase 3W6EOK1O: I Cannot See My COM Ports in Measurement and Automation Explorer (MAX)
KnowledgeBase 270AN336: Why Are My Serial Ports Missing in MAX?

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Report Date: 09/17/2004
Last Updated: 05/01/2008
Document ID: 3DG8368O

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