HP Sander 16500C manual Query Usage

Example

Introduction to Programming

Query Usage

Query Usage

Logic analysis system instructions that are immediately followed by a question mark (?) are queries. After receiving a query, the Logic Analysis System parser places the response in the output buffer. The output message remains in the buffer until it is read or until another instruction is issued. When read, the message is transmitted across the bus to the designated listener (typically a controller).

Query commands are used to find out how the system is currently configured. They are also used to get results of measurements made by the modules in the system.

This instruction places the current full-screen time for machine 1 of the logic analyzer module in slot 2 in the output buffer.

:SELECT 2:MACHINE1:TWAVEFORM:RANGE?

In order to prevent the loss of data in the output buffer, the output buffer must be read before the next program message is sent. Sending another command before reading the result of the query will cause the output buffer to be cleared and the current response to be lost. This will also generate a "QUERY UNTERMINATED" error in the error queue. For example, when you send the query :SELECT 2:TWAVEFORM:RANGE? you must follow that with an input statement. In BASIC, this is usually done with an ENTER statement.

In BASIC, the input statement, ENTER XXX; Range, passes the value across the bus to the controller and places it in the variable Range.

Additional details on how to use queries is in the next section of this chapter, "Receiving Information from the Logic Analysis System."

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