National Instruments 778956-01 MXI-4 Bus Expansion Card

The part number 778956-01 from National Instruments is the identifying part number for the PCI-8331 MXI-4 Bus Expansion Card. The MXI-4 PXI Bus Expanders provide direct control of PXI systems via any PCI slot in a desktop or server. MXI-4 interface cards can also be used to connect several PXI chassis. MXI-4 technology uses high-bandwidth communication that is transparent to software programs and drivers, allowing high-performance desktop PCs or servers to control PXI equipment.

The 778956-01 MXI-4 Bus Expansion Card has a data transfer rate of up to 1.5 Gbit/s. This expansion card supports the daisy chain or star configuration. With daisy chain configuration, all devices are connected in series from the source until the data or the message reaches the destination. The star configuration is a much simpler and more reliable topology where all the devices are connected to a single master device and the master uses a particular device address to send data to a particular module or device.

This MXI-4 Expansion Card supports the MXI-4 software and NI-VISA driver. The module is only compatible with copper cables for power and data transmission and requires at least 10 meters of wire for power connection. This module does not feature a cooling fan and is reliant on two heatsinks attached to its DSP and Microcontroller chips. To enhance cooling it is recommended to install this card in an environment with a temperature between 0 degrees Celsius and 55 Degrees Celsius for optimum performance. The drive can also operate in highly humid conditions with up to 90 % humidity without moisture affecting the internals of the module. 

The MXI-4 Expansion Card attaches directly to the main supported control unit. This card has an easy-to-install snap-on design and has compact dimensions of 4.2 inches x 6.9 inches. The vibrational rating this module has is 0.3 g during operation and 2.4 g during idle situations with vibration frequencies between 5 and 500 Hz. The card has an open type enclosure with an IP 00 rating making it vulnerable to harsh industrial environments and hence must be installed in clean environments.