Getting Started 3Keysight InfiniiVision 4000 X-Series Oscilloscopes Programmer's Guide 77The easiest method of transferring a digitized waveform depends on datastructures, formatting available and I/O capabilities. You must scale the integers todetermine the voltage value of each point. These integers are passed starting withthe left most point on the instrument's display.For more information, see the waveform subsystem commands and correspondingprogram code examples in Chapter 34, “:WAVeform Commands,” starting on page1233.Reading Query Responses from the OscilloscopeAfter receiving a query (command header followed by a question mark), theinstrument interrogates the requested function and places the answer in its outputqueue. The answer remains in the output queue until it is read or anothercommand is issued. When read, the answer is transmitted across the interface tothe designated listener (typically a controller).The statement for reading a query response message from an instrument's outputqueue typically has a format specification for handling the response message.When using the VISA COM library in Visual Basic, you use different read methods(ReadString, ReadNumber, ReadList, or ReadIEEEBlock) for the various queryresponse formats. For example, to read the result of the query command:CHANnel1:COUPling? you would execute the statements:myScope.WriteString ":CHANnel1:COUPling?"Dim strQueryResult As StringstrQueryResult = myScope.ReadStringThis reads the current setting for the channel one coupling into the string variablestrQueryResult.All results for queries (sent in one program message) must be read before anotherprogram message is sent.Sending another command before reading the result of the query clears the outputbuffer and the current response. This also causes an error to be placed in the errorqueue.Executing a read statement before sending a query causes the controller to waitindefinitely.The format specification for handling response messages depends on theprogramming language.NOTE Aborting a Digitize Operation Over the Programming InterfaceWhen using the programming interface, you can abort a digitize operation by sending a DeviceClear over the bus (for example, myScope.IO.Clear).
