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National Instruments 777997-01 GPIB Extender 

National Instruments part number 777997-01 is an identifying part number for the GPIB-140A a GPIB Extender.  This device effectively extends the cable length and device loading limitations imposed by the IEEE 488 standard. The NI 777997-01 is fully compliant with IEEE 488.1 and IEEE 488.2 standards, which specify a maximum system length of 20 meters. With a pair of GPIB Extenders like the 777997-10, the total distance can be extended up to 1 km without any modifications, maintaining the integrity of the GPIB system. Each unit continuously monitors GPIB activity and converts GPIB signals into serial or parallel signals for transmission over long distances. At the receiving end, the extender converts these signals back into IEEE 488 signals. 

Importantly, this Extender is transparent to existing software applications, requiring no modifications for seamless integration. This GPIB Extender supports fiber-optic cables up to 1 km in length. The NI 777997-01 utilizes a buffered transfer technique, making it one of the fastest GPIB Bus Extenders available, achieving speeds greater than 2.8 Mbytes per second when using the HS488 protocol. Setting up this extender is straightforward and does not require additional hardware. In a typical setup, a computer device connects to one end of a cable extender, while a GPIB instrument connects to the other end of a similar extender. 

These extenders are then linked together via a fiber-optic cable for extended-distance communication. Moreover this GPIB Extender utilizes a transmission cable with a diameter of 3.0 × 6.5 mm, designed for robust performance. The cable features a 62.5/125 micron core/clad configuration with a numerical aperture (NA) of 0.275, optimized for transmitting signals efficiently. Operating at an 850 nm wavelength, it exhibits an attenuation of 3.0 dB per kilometer, ensuring reliable signal integrity over long distances. 

The cable is of duplex style, terminated with ST-style connectors, which provide secure connections and easy installation. The transmission interface unit of the 777997-01 incorporates optical transmitter and receiver components (such as HFBR1414, HFBR2416, or equivalent models) with ST-style optical cable connectors, facilitating seamless communication between GPIB devices over extended distances using fiber-optic technology.