National Instruments GPIB-120B

 NATIONAL INSTRUMENTS GPIB-120B Bus Expander/Isolator  

The National Instruments GPIB-120B is a GPIB bus isolator and expander. You can use it in test and measurement systems to provide electrical isolation as well as expand the number of devices allowed on the GPIB bus.  The NI GPIB-120B provides an electrically isolated interface to one or more GPIB devices. It offers up to 2,500 VDC of noncontinuous isolation between the GPIB ports and between each GPIB port and the power supply, based on a 5 s dielectric withstand test.

The GPIB-120B also expands the number of devices allowed on the GPIB. The IEEE 488.1 standard prescribes a maximum of 15 electrical device interface loads in a GPIB system. The GPIB-120B increases the number of GPIB system devices from 15 to 28. It also provides bidirectional expansion, where controllers, talkers, and listeners can exist on either side of the expansion.  The GPIB-120B isolator/expander can operate in one of two data transfer modes: unbuffered and buffered. The data transfer mode determines how data is transmitted across the expansion. The GPIB-120B is capable of data transfers of up to 1.2 MB/s in buffered mode and up to 450 kB/s in unbuffered mode.

Specifications for the  NATIONAL INSTRUMENTS GPIB-120B Bus Expander/Isolator Include:

• IEEE 488.1 and IEEE 488.2 compatible  
• 60 VDC continuous electrical isolation  
• 2,500 VDC noncontinuous overvoltage isolation between GPIB ports and between each port and power supply based on 5 s withstand test  
• Transfer rates  
• Up to 1.2 MB/s (buffered mode)  
• Up to 450 kB/s (unbuffered mode)  
• Expands the number of GPIB devices allowed on the bus to 28