PAR24B USER MANUAL EXCERPTS

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The table of contents and selected excerpts from the PAR24B manual are shown below. The full text is available in PDF format at no charge from our downloads page.

CHAPTER 1: INTRODUCTION
The Symmetric Research PAR24B A/D data acquisition board provides an easy way to acquire high resolution data on your PC from 8 channels at low sampling rates. It has been designed to work in conjunction with EPP/BPP parallel ports supported by most current PCs. Interfacing to the parallel port, the system is ideal for use with PCs such as laptops where adding in an ISA or PCI bus card is not possible.

Based on the Harris HI7190/HI7191 24 bit sigma delta A/D converter, the SR PAR24B has an individual A/D converter for each channel, minimizing channel cross talk, skew, and settling time. You get the full performance of a dedicated A/D converter on each channel. In addition all data from the A/D converters is FIFO buffered. This allows for continuous data acquisition even with long Windows task switching latencies.

Software included with the board is aimed at familiarizing the user with its technical operation and providing a high level interface. Win 95 32 bit DLL library functions are at the core of the software support, taking care of low level interfacing with the hardware. Example programs written in C show how to carry out basic operations, while finished Win 95 and DOS applications allow the user to immediately begin using the system. Virtual Instrument drivers and finished applications are also provided for National Instruments LabView.

Other items included with the board are a 9 vac power supply, a molded cable for connecting to the PC's parallel port, analog input test leads, complete circuit diagrams, and source code.

CHAPTER 2: INSTALLATION
Installation of the PAR24B is straightforward. You'll need to connect the power, connect the PC parallel port, install the software, and provide suitable analog inputs. The individual steps in more detail are:

CHAPTER 3: DLL LIBRARY SUPPORT
Win 95 32 bit DLL library support is at the core of the software supplied with the SR PAR24B board. With these functions, board operation can be controlled from high level languages without having to know the low level details of how the board operates. These functions can be called from Microsoft Visual C and Basic, and National Instruments LabView. This chapter covers usage from programming environments like Visual C. For information about usage from LabView, see the LabView chapter.

The outline of how to use the par24b.dll functions is fairly simple. First call the Init function to set the sampling rate and other parameters. Once the board has been initialized, the Start function should be called to begin execution. While executing, IsReady should be used to determine when the PAR24B FIFO is half full with acquired data. Then use GetData to move the data from the FIFO into a PC memory array, after which it can be displayed or saved to the hard disk.

CHAPTER 4: FINISHED APPLICATIONS
The SR PAR24B comes with two finished application programs you can run immediately after installing the system. These programs not only help you become more familiar with the system, but also may fill your entire acquisition needs. The source code is included for those wanting to modify these programs for custom applications.

The \sr\par24b\simple\simp24b.exe and \sr\par24b\scope\scope24b.exe programs have both been written in C with simp24b.exe being a simple text only command line program, while scope24b.exe has a full Win 95 GUI graphical interface and display.

CHAPTER 5: LABVIEW SUPPORT
Support for National Instruments LabView is provided in the LabView LLB VI library \sr\par24b\labview\par24b.llb. This LLB contains 3 application and 14 utility VIs. The application VIs include complete data acquisition programs that rely on the underlying utility VIs. The utility VIs are in turn wrappers around the corresponding core par24b.dll DLL functions which supply the low level support for all SR PAR24B software.

The PAR24B application VIs are described below. For additional information, please refer to the descriptions of the underlying DLL functions or use the Window>Show VI Info... menu option to access the information stored within each VI itself. The VIs have been saved unlocked and with their block diagrams included so that you can modify them as needed to fit your application.

APPENDIX A: ELECTRICAL SPECS & CALIBRATION
Note: for additional specs such as A/D resolution, please check the Harris HI7190 A/D chip specs.

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