National Instruments GPIB-120B Manual

Also see for GPIB-120B: User manual Installation guide

Contents

National Instruments GPIB-120B Manual Manual pdf 18 page image

Chapter 2 Hardware OverviewGPIB-120B User Manual 2-4 ni.comSetting the Data Transfer ModeTo use buffered mode, set the switch to the ON position, as shown inFigure 2-2. To use unbuffered mode, set the switch to the OFF position.Figure 2-2. Switch Setting for Buffered ModeNote The placement of the switch to select buffered or unbuffered mode is recessed toavoid unintentional toggling during operation of the GPIB-120B. To flip the switch,a flathead screwdriver or similar tool may be required.Verify that the switch on your GPIB isolator/expander is in the desiredposition before powering on the unit.Data Direction ControlBus B sends the data lines to Bus A if the Bus B Source Handshake state istrue or if a Controller on Bus A is conducting a parallel poll.Bus A sends the data lines to Bus B if the Bus A Source Handshake state istrue or if a Controller on Bus B is conducting a parallel poll.Parallel Poll DetectionControllers can conduct parallel polls on Bus A or Bus B, and devices onboth Bus A and Bus B can respond to parallel polls.If a Controller on Bus A conducts a parallel poll, the parallel poll detectioncircuitry on side B conducts a parallel poll on Bus B. The result of theparallel poll is driven on the data lines of Bus A.If a Controller on Bus B conducts a parallel poll, the parallel poll detectioncircuitry on side A conducts a parallel poll on Bus A. The result of theparallel poll is driven on the data lines of Bus B.Refer to the Parallel Poll Operation section in this chapter for importantinformation about conducting parallel polls with the GPIB-120B.ON OFFBUFFERED