National Instruments GPIB-120B GPIB Expander/Isolator

The NI GPIB-120B (Part Numbers: 779651-01, 779651-04, 779651-06, and 779651-07) is a GPIB Bus Expander/Isolator. This model is fully compatible with IEEE 488.1 and IEEE 488.2 standards. With this model, the user can expand the limit of allowable devices on the GPIB bus to as many as 28. Thus, this Expander/Isolator can be used in a variety of test and measurement systems.

The GPIB 120B Bus Isolator Expander offers great isolation capabilities because it can provide up to 2,500 VDC of isolation (non-continuous) between the GPIB ports, the power supply, and every individual GPIB port. With this model, bidirectional expansion of GPIB system devices can be achieved where talkers, listeners, and controllers can exist on either side of the expansion.

The NI GPIB-120B can effectively eliminate induced common-mode noise and ground loop noise by operating as an isolating bearer between instruments and an IEEE 488 bus controller. Each GPIB-120B enables the user to add as many as 14 additional devices to the GPIB bus. Functionally, this device operates transparently. Therefore, the GPIB control and communication programs that work with the unexpended system can be utilized with an expanded system as well.

This Expander/Isolator offers two data transfer modes: buffered mode and unbuffered mode. In its standard configuration, unbuffered transfer mode is set as the default switch setting. However, users can select their desired data transfer mode by using the switch provided on the back of the unit. The NI GPIB-120B comes featured with eight data lines (DIO1, DIO2, DIO3, DIO4, DIO5, DIO6, DIO7, and DIO8) and three hardware handshake lines.