A Standard Data Format for instrument data interchange - HP's SDF standard for analyzers - Technical

Hewlett-Packard Journal, Dec, 1993 by Michael L. Hall

This standard format allows many HP analyzers to exchange data with each other and with applications software. Utilities provide data conversion, editing, viewing, and plotting and a function library provides access to SDF data from programs.

The Standard Data Format (SDF) is a record-based binary data file format that is used to store data from a variety of analyzers manufactm'ed by the Hewlett-Packard Lake Stevens Instrument Division. These analyzers range from portable acoustic analyzers and low-frequency FFT analyzers to RF vector signal analyzers (see Fig. 1). The SDF file format is flexible enough to contain multiple channels of data, multiple data results in a single file, multiple scans of a data resuit (waterfall), and deep capture of contiguous time data. The HP 894xxA vector signal analyzer described in the article on page 6 uses SDF to store trace data (single results), time capture data (up to one million time samples), and waterfall data.

Included with each instrument that saves data files is the Standard Data Format utilities, a set of MS-DOS programs that make it possible to convert data from one format to another, edit SDF records and data, graphically view data, and plot (single or batch) data from SDF files. Fig. 2 lists the SDF utilities.

Interchangeability

Storing data in SDF format allows many instruments and applications to interchange measurement data, time capture data, and waterfall or map data (see Fig. 1).

Since the amount of memory varies from instrument to instrument, there are restrictions on the amount of data that each instrument can import from another source. For example, the HP 894xxA vector signal analyzer with Option AY9 is restricted to one million samples of time capture data. Other instruments, depending upon the amount of memory purchased, have other restrictions.

Direct Exchange        Exchange                Supported
(Supports MS-DOS)   through Translator  Application/Data Formats

HP 89410A             HP 3562A                Spreadsheets
HP 89440A             HP 3563A                General ASCII Data
HP 35665A             HP 35660A               MATLAB
HP 35670A             HP 3560A                MATRIXx
HP 3566A              HP 3569A                Data Set 58
HP 3567A              HP 3588A                Libraries
                      HP 3589A
                      HP 3587S
Fig.1 Standard Data Format supported instruments and applications.

The HP 894xxA contains a 3.5-inch flexible disk drive that supports both MS-DOS and HP Logical Interchange Format (LIF) file systems. SDF data stored on a DOS file system can be directly interchanged between tiffs analyzer and other instruments in the first column of Fig. 1 by exchanging disks.

Other instruments either do not store data directly in SDF format or do not support MS-DOS flexible disks. The SDF utilities include programs to translate instrument data from other formats to SDF (see "Instrument Translators" in Fig. 2).

Interface
  LIF          Logical Interchange Format flier
  LIFDIAG      UF diagnostics
  DOWNLOAD     Download HP 3560A or HP 3569A file via RS-232
  HPIB63       Transfer HP 3562A or HP 3563A traces via HP-IB

Instrument Translators
   63TOSDF         HP 3562A or HP 3563A to SDF
   SDFT063         SDF to HP 3562A orHP 3563A
   660TOSDF        HP 35660A to SDF
   6OTOSDF         HP 3560A to SDF
   69TOSDF         HP 3569A to SDF
   88TOSDF         HP 3588A to SDF
   89TOSDF         HP 3589A to SDF

Application Converters

   SDFTOASC        SDF to ASCII format
   SDFTOML         SDF to MATLAB matrix format
   SDFTOMX         SDF to MATRIXx matrix format
   SDFT058         SDF to Data Set 58
Examining Files
   VIEWOATA        Graphically view SDF data
   REPEAT          Repetitively execute another program
                   (e.g., batch plot)
   SDFPRINT        Textually view SDF headers
Changing Files
   ASCTOSDF        ASCII data to SDF
   SDFEDIT         Change SDF headers
   SDFTOSDF        Split SDF file

Program Interlace

   SDFUTIL         SDF libraries
   FILTERSDF       MATLAB filter time capture files

Fig. 2. The Standard Data Format utilities.

Foreign File Systems

Some instruments do not support MS-DOS as a file system, but do support LIF, including the HP 3562A, HP 3563A, HP 35660A, HP 3588A, and HP 3589A analyzers. To support data interchange with these instruments, the SDF utility LIF can read and write on a LIF disk in the computer's internal disk drive or an HP-IB connected external disk drive. The utility LIF can:

* Identify HP-IB card location and any connected external disk drives

* Copy files to and from LIF disks using optional wild-card file names

* Delete LIF files

* List a LIF directory

* Initialize a LIF disk.

In addition, the SDF utility LIFDIAG performs LIF disk backups even when a disk is damaged. It includes the ability to read, modify, and write individual disk sectors (256-byte blocks).

The HP 3560A and HP 3569A analyzers are battery-powered portable instruments that contain a nonvolatile RAM disk and have an RS-232 interface. The SDF utility DOWNLOAD can transfer a file from the instrument to the computer via RS-232. In addition, the extended data transfer utilities for the HP 3569A contain FILE69, a filet that can bidirectionally transfer groups of files via RS-232.