Overview of the GPIB Parallel Port Controller Functionality
PrintThe parallel port controller allows you to control GPIB devices from the parallel port of your computer. This functionality is good for laptops and other computers that do not have plug-in slots, but do have a standard parallel port. Additionally, the parallel port controller is good for applications that require high-speed data transfer rates. The parallel port controller is completely IEEE 488.2 compatible, and can control a maximum of 14 instruments. The parallel port controller allows you to program your GPIB instrument using the 488M or 488.2M command set.
The controller has two parallel ports. The first port allows connection to the host computer. The second parallel port allows you to connect to a parallel port instrument, such as a printer. When the controller powers on, all parallel port activity from the computer routes directly to the pass-through parallel port connection. When the NI-488.2 driver software executes GPIB commands and performs data transfer, it sends a data sequence to the controller. This data sequences tells the controller to act like a GPIB board.
The parallel port controller supports the ISA Unidirectional Parallel Port, the PS/2 Bidirectional Parallel Port, and the Enhanced Parallel Port (EPP). The primary application for the unidirectional PC parallel port is to connect to printers. New PCs and the IBM PS/2 line have bidirectional parallel ports that facilitate communication with input and output devices. The high-speed parallel port is ideal for use in instrument control systems. The EPP makes the parallel port better suited for connecting to peripheral devices. The goal of the EPP was to make the parallel port a bidirectional interface with increased maximum transfer rates. The EPP can achieve high transfer rates, up to 2 Mbytes/s.
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