Chapter 3

VXI Programming Using the IEEE 1394 Serial Bus

Using this Chapter

Programming

Register-Based and

Message-Based VXI

Instruments

Opening Instrument Sessions

This chapter contains examples and general information for programming VXI systems over the IEEE 1394 serial bus. The contents of the chapter include:

•Programming Register-Based and Message-Based

Instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

• Opening Instrument Sessions . . . . . . . . . . . . . . . . . . . . . . . . 35

• Optimizing Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

• HP E8491A Triggering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

• Using HP E8491A Shared Memory . . . . . . . . . . . . . . . . . . . 47

There are no SCPI instrument drivers for register-based instruments installed in, or downloaded to the HP E8491A. Therefore, register-based instruments are programmed over the IEEE 1394 bus using either their VXIplug&play drivers, or through register-level peeks and pokes using HP VISA or SICL.

Message-based instruments are programmed using HP VXIplug&play drivers, or using SCPI commands embedded in HP VISA or SICL function calls.

VXIplug&play drivers for HP register-based and message-based instruments are contained on the HP Universal Instrument Drivers CD which ships with each HP VXI instrument.

Programs which run over the IEEE 1394 interface begin by opening a session between the VXI instrument and the driver or I_O library (VISA or SICL). An address that includes the interface name and number (described in Chapter 2) and the instrument’s logical address is used in opening these sessions.

Following are three segments that open sessions to an instrument in HP VXIplug&play, HP VISA, and SICL programs.

HP VXIplug&play

ViSession vi;

//open device (VXIplug&play) session to the HP E1563 errStatus = hpe1563_init(“VXI0::24::INSTR”,VI_FALSE, VI_FALSE, &vi);

Chapter 3

VXI Programming Using the IEEE 1394 Serial Bus 35