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GPIB Troubleshooting Resources
NI Spy Utility
This document introduces you to NI Spy, a Win32 utility that monitors and records multiple National Instruments APIs
(for example, NI-488.2 and VISA).
Overview
NI Spy monitors, records, and displays the NI-488 and NI-488.2 calls made to the GPIB driver from Win32, Win16, and DOS
GPIB applications. It is a useful tool for troubleshooting errors in your application and for verifying that the
communication with your GPIB instrument is correct.
Starting NI Spy
To start NI Spy, select the NI Spy item under Start»Programs»GPIB Software. When you launch NI Spy, it displays the main
NI Spy window. By default, capture is off. Start capture by clicking on the blue arrow button in the NI Spy toolbar.
Then, start the GPIB application that you want to monitor. NI Spy records all GPIB calls made to the GPIB driver.
The figure below shows the main NI Spy window with several recorded calls.
Using the NI Spy Online Help
The NI Spy utility has built-in, context-sensitive online help that describes all NI Spy features. To access it, select
Help from the NI Spy menu. You can also access the online help by clicking on the question mark button in the NI Spy
toolbar, and then clicking on the area of the screen about which you have a question.
Locating Errors with NI Spy
All GPIB calls returned with an error are displayed in red within the main NI Spy window.
Viewing Properties for Recorded Calls
To see the detailed properties of any call recorded in the main NI Spy window, double-click on the call. The Call
Properties window appears. It contains general, input, output, and buffer information. The figure below shows the Buffer
tab for a device-level ibwrt call.
Exiting NI Spy
When you exit NI Spy, its current configuration is saved and used to configure NI Spy when you start it again. Note that
unless you save the data captured in NI Spy before you exit, that information is lost.
To save the captured data, click on the red X button on the toolbar and select File»Save As to save the data in a .spy file.
After you save your data, select File»Exit to exit the NI Spy utility.
Performance Considerations
NI Spy can slow down the performance of your GPIB application, and certain configurations of NI Spy have a larger impact on
performance than others. For example, configuring NI Spy to record calls to an output file or to use full buffers might
have a significant impact on the performance of both your application and your system. For this reason, use NI Spy only
while you are debugging your application or in situations where performance is not critical.
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