VXI Multi-Chassis Comparison

Hardware: GPIB>>Plug-in Controllers>>GPIB-VXI/C

Problem:
What are different configuration options when configuring a multi-chassis VXI system and what are the benefits and/or drawbacks to each method?

Solution:
MXI-2
MXI-3
VXI-1394
VXI-USB
GPIB-VXI

	MXI-2
Advantages	High Speed Add/Remove Cards without Controller Reboot
Disadvantages	Limited LAs (256 per Contoller) Short (20m) Cable Length

NI Products
Controller Kits (PC Side and MXI-2 Extender for various Operating Systems)
NI VXI-PCI 8015
NI VXI-PCI 8012
NI VXI-PCI 8010
NI VXI-PCI 8040
NI VXI-PCI 8022
NI VXI-PCI 8024
NI VXI-PCI 8026
MXI-2 Extenders
NI VXI-MXI-2
NI VME-MXI-2

	MXI-3
Advantages	Long (200m) Cable Length
Disadvantages	No Sharing Triggers between Chassis

NI Products
Copper MXI-3 (30m max length)
NI VXI-PCI 8340
Fiber Optic MXI-3 (200m max length)
NI VXI-PCI 8345

MXI-3 overcomes the MXI-2 length limitation, but since it is not a pure bus-extender like MXI-2, triggers and clocks can't be shared via the MXI-3 cable. Also, each controller will show up as a separate VXI System in Measurement & Automation Explorer (MAX) because each MXI-3 card is a separate system. This also overcomes Logical Address (LA) limitations (256 max) for VXI systems.

	VXI-1394
Advantages	Uses Standard 1394 Technology
Disadvantages	No Sharing Triggers

VXI-1394 is very similar to MXI-3, except it may reduce costs because only a VXI-side card is needed and a standard 1394 controller card can be used to control it. It also has two additional 1394 ports (three ports minus the one in use to control the chassis) which can be used to connect any other 1394 device (i..e hard drive, firewire camera ,etc)

NI Products
IEEE 1394 VXI Controller

	VXI-USB
Advantages	Uses Standard USB Technology. Fast transfer rate of up to 480 Mb/s
Disadvantages	No Sharing Triggers

VXI-USB is very similar to VXI-1394 or MXI-3, except it may reduce costs because only a VXI-side card is needed and a standard 1394 controller card can be used to control it. Taking advantage of USB 2.0 technology, the VXI-USB achieves a superior throughput for block transfers and word-serial (message-based) communication in comparison to IEEE 1394 (FireWire)-to-VXI and GPIB-to-VXI interfaces. It also has 2 additional USB ports to connect to 3rd Party devices.

NI Products
NI VXI USB Controller

	GPIB-VXI
Advantages	Inserts into existing GPIB system Works well with Message-Based Devices
Disadvantages	No Sharing Triggers Limited Number of Devices Relatively Slow

The two configurations are either Parallel or Star. Parallel would consist of having more than one GPIB board in your PC and connecting to multiple VXI chassis. This would optimize throughput. The second case (Star) would be to connect 1 or more additional GPIB-VXI controllers at the GPIB junction connected to the first. In this case you could Star configure off the second or third controller (it does not need to be the first). Making if more like a daisy-chain configuration (this would give additional length).

NI Products
NI GPIB-VXI/C6