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In some cases, these drivers are just one way to communicate. For the E6432A microwave synthesizer, its plug&play driver is the only means of communication with the host controller or its application programs. This product note provides an overview of the communication process, the range of hardware and software configurations supported, and an introduction to the features of the instrument made available through the plug&play driver. The E6432A microwave synthesizer is a register-based device, rather than a message-based device. There are two reasons for this. First, the E6432A is designed to be a system source rather than a bench source, so its user interface and command set are simple and straightforward. A register-based design supports this application. Secondly, the E6432A employs a fast-switching architecture in both frequency and amplitude switching. Switching times of less than 400 .s can be achieved in real customer applications only if the E6432A processing time is kept to well under 50 .s. This can only be accomplished with a register-based design. Most modern automated test systems use programming environments and VXI interfaces that support the plug&play driver architecture. These systems will easily integrate the E6432A. For systems using older, legacy software and VXI interfaces, support for the E6432A may require rewriting and/or changing interfaces. These conditions will be covered in this note. Programming Environments To support the E6432A plug&play driver, the operating system foundation required by the host controller is Microsoft Windows NT® 4.0, with Service Pack 3 or above installed. Other operating systems, such as Windows 95/98, UNIX®, or MacOS are not supported at introduction. Application programs running on Windows NT that are compatible with the E6432A plug&play driver are: HP VEE 4.0 or higher National Instruments LabView and LabWindows/CVI versions 4.0 or higher Microsoft Visual Basic version 5.0 or higher Microsoft Visual C/C++ versions 5.0 or higher Application programs such as Agilent Basic for Windows have no provision for communicating with plug&play drivers and are therefore not supported. VXI Interfacing There are several interfacing choices available from host controller to VXI instruments. Three of these are supported by the E6432A plug&play driver. They are: VXI Embedded Control (for exam ple, E6234A running Windows NT) National Instruments VXI-MXI-2 IEEE-1394 ("Firewire") (for example, E8491A) The remaining VXI interfaces (HP and National Instruments GPIB-VXI, and National Instruments MXI-1) are unsupported. The VXI data specification for the E6432A is A16/A24, D16/D32. Due to the large size of frequency registers, floating point arithmetic is a must. The interface must be capable of allocating a large block size of A24 address space (256k). GPIB interfaces are unsupported because they are fundamentally message-based interfaces. They are not designed to communicate with register-based instruments without special, proprietary software that must be written and downloaded into their memories prior to using the plug&play driver. Microsoft, Windows and Windows NT are U.S. registered trademarks of Microsoft Corporation. UNIX is a registered trademark of the Open Group. National Instruments has two versions of the MXI interface that are usable in a host controller. The older VXI-MXI-1 slot 0 controller and its host card (the AT-MXI interface) do not operate correctly with E6432A, due to the AT-MXI interface’s inability to access more than 64k of A24 address space. (Remember, a minimum of 256k is required.) The newer MXI interface from National Instruments (the VXI-MXI-2 interface) and its host controller card (the PCI-MXI interface) work properly with all of the application programs listed. A new serial interface for VXI based on IEEE-1394 is available from Agilent (the E8491A). This interface has nearly the same performance as MXI-2 in many applications. The E8491A is supported for use with the E6432A. Embedded controllers are available from both Agilent and National Instruments. Those controllers that contain the Intel Pentium® processor and run Microsoft Windows NT 4.0 are supported for use with the E6432A. Initializing the Instrument After installing the interfaces and drivers using the procedures given in the user documentation, it is time to apply power to the VXI mainframe and check out the system. Register-based devices typically do not contain a processor and firmware that perform bootstrap and self-test functions at power on. These functions are jointly executed by the host controller and the device. For the E6432A, the functions are performed when the host controller issues the ViInitialize function call through the plug&play driver. When power is first applied to the E6432A, the red FAIL LED is lit. This LED remains lit until a successful completion of the ViInitialize function call. Within this function call are commands that: issue the bootstrap com...