Greetings IVI Experts, Most IVI class drivers seem to define an IVI class driver timeout error code. For instance IviScope defines (in iviscope.h): #define IVISCOPE_ERROR_MAX_TIME_EXCEEDED (IVI_CLASS_ERROR_BASE+0x0003L) That error code is BFFA2003. In the specific IVI driver code, if VISA returns the timeout code (BFFF0015), the returned error code is changed to BFFA2003. VISA defines the timeout code as such (in visa.h): #define VI_ERROR_TMO (_VI_ERROR+0x3FFF0015L) /* BFFF0015, -1073807339 */ It turns out other IVI classes (IviDmm, IviPwrMeter, IviRfSigGen, IviSpecAn, IviSwtch) define their own maximum time exceeded code , but not IviFgen. That means no error conversion for class IviFgen. That seems rather odd. Anybody knows why? These files seem to be under IVI Foundation's control.

Scipio, If you look at sections 4.3.9 and 5.3.7 of the IviSwtch class specification, they define two functions (WaitforDebounce and WaitForScanComplete) that return the Max Time Exceeded error. (I said "read/fetch data functions and some other functions"). This is why the class driver defines this error code. There is no such function in the IviFgen class. You will find similar examples in the other class specifications you mentioned. What the spec is saying is that if the driver implements the WaitForDebounce function, then it must return the IVISWTCH_MAX_TIME_EXCEEDED error code in the case of a time-out. To allow the user to write an interchangeable application for the IviSwtch API, the class driver defines this error code. Conversely, the IviFgen class API does NOT define this errror code because it will not be used by a class-compliant IviFgen application, since there is no function in the IviFgen spec that returns this error code. Sure, a specific driver can choose to translate a VISA time-out error to an IVI time-out error code for any number of functions, in which case it will define the error code in its header.

Instrument Control (GPIB, Serial, VISA, IVI)

Why not IVIFGEN_ERROR_MAX_TIME_EXCEEDED?

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Thanks, z_haider, this answers the question indeed. I guess it boils down to the IVI Foundation's decision that no functions will return an IviFgen class timeout error code, therefore no need for the code.

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Instrument Control (GPIB, Serial, VISA, IVI)

Why not IVIFGEN_ERROR_MAX_TIME_EXCEEDED?

Re: Why not IVIFGEN_ERROR_MAX_TIME_EXCEEDED?