Fast Digital Integrator - From board to instrument

10.01.12

art_fdiTwo years after the first version of the FDI2056, the fastest integrator on the market, Metrolab has made a series of changes in response to users' requirements, including a standardised software interface, "trigger factory", and better time resolution. Jacques Tinembart, senior engineer at Metrolab, explains.

Developed by CERN and Sannio University to measure the LHC magnets, and licensed by Metrolab, the FDI2056 has fully lived up to its promise in terms of performance since it first hit the market in January 2010. But even the world’s best acquisition card does not necessarily make a good instrument. Customers are the best judge: "Feedback from the laboratories helped us to identify which features were lacking from our integrator board", sums up Jacques Tinembart, senior engineer at Metrolab.

The first area for improvement was the software interface. The original system, based on a PXI bus and acquisition channels, lacked a standardized communication interface. The architecture has been overhauled and now includes a full-featured embedded processor, turning the acquisition board into an instrument. It is now possible to send SCPI compliant commands through an Ethernet link to the instrument. With National Instruments’ VISA library, customers benefit from a proven, multiplatform software layer to seamlessly integrate the FDI2056 in their data collection application. "The FDI2056 thus has the same control system as other Metrolab instruments, corresponding to a standard used by major manufacturers such as National Instruments, Agilent or Tektronix", stresses Jacques Tinembart.
In addition, since many measurement benches and procedures are based on the long-lived Metrolab PDI5025, an emulation layer is also provided, enabling almost all previously designed systems to use the new FDI2056.
art_fdi_popup

Redesigned triggering scheme

Laboratories also expressed the desire to have multiple trigger sources – first and foremost, linear or rotating encoders to trigger the acquisition of partial integrals in known positions. This is now possible, as a module has been added to the integrator’s field-programmable gate array (FPGA) to process signals from such encoders. Designed to be versatile, the "trigger factory" can directly interface to all commonly used encoders, and can also trigger on an internal timer, an external input, or by software. At the same time, the acquisition time-stamp has been significantly improved"We used the digital frequency synthesizer available in the programmable gate array to increase the resolution by a factor of 6, so that it is now below 10 ns", Jacques Tinembart points out.

Several other corrections have been made to the instrument, again by exploiting the potential of the FPGA. The time lag between measurements obtained from several channels (for example, when using so-called "bucking" coils) was overcome by making full usage of the PXI bus-triggering scheme. The difference between two channels is now around 1 ns. The sample rate has also been increased, from 250 kSPS to 670 kSPS, and bus-transfer limitations have been eliminated by adding an on-board memory capable of buffering up to 1 million partial integrals.

More user-friendly… and less expensive!

In addition, the system now includes a mechanism to allow the end user to perform an upgrade in the field. Jacques Tinembart could talk about these points – and various others - in great detail, but let’s stick to the essentials: "We have worked hard to rectify all the problems our customers pinpointed in using this integrator board, and we are proud to offer them an instrument that is both efficient and user-friendly!"
The new version will be available Q1 2012. All previously sold FDI2056 systems will have to make a quick trip back to Metrolab, where the necessary hardware will be added in order to update the card. After that, it will be simply a matter of downloading any later improvements.
And to conclude, Metrolab's sales manager Claude Thabuis has another good piece of news to announce: this new version of the FDI2056 will also be… less expensive! While the cost of the card remains the same, that of the crate (with an embedded controller replacing the PCI bridge) is significantly lower: "The final cost of the crate system will be at least 32% less, depending on the configuration chosen". And existing customers can have their FDI2056 cards upgraded for free (except for shipping). That’s what one calls integral support!