New modular instrument standard cuts cost, complexity25 Sep 2014 | Larry Desjardin
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We focused on switching systems, which are very challenging. They are cost sensitive and don't scale down in size with Moore's law. Therefore, large board sizes are needed for high channel counts. With electronic test assembled in EIA cabinets, deep modules have better rack space efficiency than shallower modules. This is what makes AXIe, with just a hair shorter depth than VXI but 14 per cent larger overall, so attractive in a replacement system, especially in large switching systems.
My job was a facilitator. I led the agenda, focused conversations on each specific technical subject and drove convergence when I saw a consensus forming. The thrill of working with architects to create a new platform or standard never grows old. It never seems possible when you begin, but the solution seems obvious when you are done.
So, let me describe AXIe-0. AXIe-0 retains the module size and board area of the current AXIe-1 Base Architecture, while delivering a cost effective platform for vendors and users not needing the full capability of AXIe-1. The module is 1.2in thick, 11in deep, and 12.7in wide (or tall) depending on whether the module is horizontal or vertical. Like AXIe-1, a chassis may have anywhere from two slots to 14.
Figure 1: The image shows the board size of AXIe-0. Several connectors are eliminated, significantly reducing chassis and module costs. There is a single -48V power supply.
The cost savings come from simplifying the power, cooling, management and backplane. An entry level AXIe-0 chassis consists of a LAN GbE switch, a 12-lane 100MHz AXIe trigger bus, and 50W/slot cooling and power. That's it! No specialised controllers, interface cards, chassis controllers and so forth. With AXIe's single -48V power supply, this chassis is tailor-made for low-cost manufacturing.
If the 50W/slot limit is too restrictive, AXIe-0 chassis and modules can add standard AXIe-1 management which, among other useful things, manages power and cooling robustly past 200W/slot. This specifically addresses the issue of high power VXI modules.
And, just as a reminder, every single one of these AXIe-0 modules will work in today's AXIe-1 chassis, starting day one. This means current AXIe-1 chassis may be used to host AXIe-0 development.
Figure 2: AXIe-0 chassis, like AXIe-1, is scalable from two slots to 14. The availability of small horizontal chassis makes AXIe a feasible choice, even for small module counts, alone or with other instruments and architectures. The "half-filled chassis" syndrome is avoided.
Why choose LAN? AXIe-0 modules are essentially simple, fast LXI devices. LAN brings all sorts of benefits, if it can provide the speed. So, we made it fast. SCPI is NOT required (just as in LXI). By eliminating the SCPI parser, command execution time drops from milliseconds to the time needed to process the TCP/IP stack, about 200µs (and declining with each processor generation). This is well faster than any mechanical switch it would control.
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