Debugging

Use I/O Trace and the VISA - Instrument Register Viewer to debug WTS applications that return errors or unexpected results. You can use I/O Trace on the client PC or the virtual instrument to observe the commands sent to and from the instrument.

• I/O Trace (client)—I/O Trace on the client PC shows the commands sent to and from the instrument, and the timestamps for when each command is received and returned. You can launch I/O Trace from the VISA Test Panel.
  Note You must install NI-VISA on the client PC to use I/O Trace on the client PC.
• I/O Trace (virtual instrument)—I/O Trace on the virtual instrument shows the instrument activity. Timestamps and tracing are slightly different on the instrument side, and may provide more information than what is available through I/O Trace on the client PC. I/O Trace on the client PC can only show activity on that client. On the instrument side, I/O Trace can show activity on all clients.

The VISA - Instrument Register Viewer shows the 488.2 VISA registers and error queue. Use VISA registers to debug applications and to improve the speed and efficiency of applications. The Status Byte register (*STB) indicates there's an error in the error queue. The VISA - Instrument Register Viewer will show the error. Call the SYS:ERROR[:NEXT]? or SYS:ERROR:ALL queries to return error info.