READ?

The READ? command is most commonly used with CONFigure to:

•Place the multimeter in the wait-for-trigger state (executes the INITiate command).

•Transfer the readings directly to the output buffer when the trigger is received (same action as FETCh? but the readings are not stored in internal memory as with the FETCh? command).

Subsystem Syntax

READ?

Comments • The READ? command is slower than the INITiate command since readings are formatted and sent to the output buffer as they are taken. However, the sample count and trigger count are not limited with READ? since memory is not used.

•This command causes the multimeter to start taking readings as soon as its trigger requirements are met (same as the INIT command).

•Each reading sent to the output buffer is terminated with a Line Feed (LF). The HP-IB End-or-Identify (EOI) signal is sent with the last byte transferred. If multiple readings are returned, the readings are separated by commas and EOI is sent only with the last byte.

•The output buffer capacity is 128 bytes. The multimeter remains “busy” with a full buffer until you begin removing readings from it.

•Readings are placed directly in the output buffer and are not stored in internal memory as with an INIT command. With INIT, a FETCh? command is required to transfer readings from internal memory to the output buffer. You may want to use the READ? mode of operation when readings need to be taken at a continuous rate.

•The rate the controller removes the readings from the multimeter needs to match the rate the multimeter puts them into the output buffer to keep from filling the output buffer. The multimeter will quit making measurements until you remove readings from the output buffer and make room in the output buffer for more readings.

•Related Commands: CONFigure, FETCh?, INITiate

Example Transfer Readings Directly to Output Buffer

dimension array

Dimension computer array to store 100

CONF:VOLT:DC

readings.

Function: DC voltage.

SAMP:COUN 100

Specify 100 readings per trigger.

READ?

Place multimeter in wait-for-trigger state and

 

make measurements; send readings to output

enter statement

buffer; trigger source is IMMediate by default.

Enter readings into computer.

Chapter 3

Multimeter Command Reference 113