Ethernet-based instrumentation for ATE

The emerging trend in the instrumentation industry is a move away from established parallel communications interfaces, such as GPIB and MXI-2, towards high-speed serial interfaces. The computer industry has adopted this philosophy and migrated nearly all peripheral connections to USB or Firewire. This trend is continuing with the elimination of plug-in style interfaces and the adoption of high-speed serial links. Many instrumentation manufacturers have followed these advances and introduced products that are based upon the industry standard Ethernet interface. A move towards high-speed serial interfaces clearly provides distinct advantages for instrumentation manufacturers as well as end users. Features such as data transfer rates approaching 1Gb/s, ease of cable routing and connectivity, as well adaptability with nearly every commercially available computer, make Ethernet a logical choice. There are however several areas of concern, unique to the test community, that must be addressed. One issue that faces most test system designers is instrument and switch synchronization and timing. Parallel-based architectures addressed this concern by simply extending the handshaking lines and system clocks to each mainframe or instrument distributed throughout the system. Obviously this option is not available with serial interfaces, and other solutions must be provided for this to be universally adopted. Software protocol functionality is also a major concern; the protocol loading on a typical TCP/IP stack can potentially reduce the throughput of the test system. Leveraging the advantages of TCP/IP in ATE applications, or possibly incorporating alternatives to this will also be discussed. The concept of this migration to a dedicated Ethernet instrumentation community will be discussed in detail. Advantages and disadvantages will be identified, along with clear technical recommendations.