LXI helps engineers across the globe……literally!

10 November 2008

Gary Raposa of Agilent Technologies looks at the impact that LXI can have

I have worked as a test and measurement engineer for Agilent Technologies (formerly, Hewlett-Packard) for nearly 30 years and have seen many products and technologies evolve during my career. Several years ago, when LXI (LAN eXtensions for Instrumentation) was first announced as a new technology, I have to admit that I was a bit skeptical about the touted benefits. However, I have since become a true believer in the power of LXI to simplify the lives of engineers by making it easier and faster to integrate electronic test equipment into robust, efficient systems. The following is just one example of a real experience I had during my journey to becoming a real LXI fan.

One of my responsibilities is to develop demonstrations for new Agilent instrumentation. I was developing a demo for an upcoming tradeshow in France using software to control a variety of instruments that also happened to be LXI compliant. I work in the United States in New Jersey (NJ), and after having completed the final instrument configuration and painstakingly debugging the program I wrote, I emailed a copy of the working program to my colleague, Frederic, in France. Frederic was scheduled to use the program with an identical set of instruments later that week at the tradeshow. The next day, Frederic contacted me to tell me that while testing the program and instrument configuration, the program was not working properly. It would run, but not everything was working as expected. Of course, I assured him that it worked for me in NJ, so I originally suspected a problem with his instrumentation. However, the first big benefit of LXI was about to prove me wrong.

Frederic had an identical set of instruments in France to those I used in the US, and he definitely had an exact copy of the program I used since I emailed it to him. So how could it not work? I called Frederic on the phone and confirmed that the instrumentation was the same. Since one of the benefits of LXI products is that they can be controlled from anywhere in the world via a LAN connection, I asked Frederic to send me the IP addresses of the instruments he was using. I could use those addresses in my program at my office desk in NJ to control his instruments in France since all of Agilent is on the same network. When I used the program from my desk in NJ to control his instruments in France, the program worked just fine! When he ran the same program using his computer on the exact same instruments, he experienced a problem!

I now needed to get another colleague, Conrad, involved since he was even more knowledgeable than I was on some of the equipment being used in the demo. Like me, Conrad works in the United States, but in Colorado, about 1600 miles (2600 km) away from NJ where I was. I added Conrad to the phone call with Frederic so that all three of us could talk. We gave Conrad the IP addresses of the instruments in France so he, too, could connect via LAN to the same instrumentation to monitor what was happening. One of those instruments was an Agilent 34980A Multifunction Switch/Measure Unit, an LXI Class C compliant product. LXI compliant products must have a built-in web server that can be accessed from any standard web browser. Conrad was using the 34980A web server to monitor its status. Like many Agilent instruments, the 34980A goes well beyond the LXI requirements for the built-in web server by providing extra monitor and control capability using the server. One of the many useful 34980A web server monitoring features is the remote I/O traffic log. The I/O traffic log captures all of the commands that are sent to the instrument enabling us to examine the SCPI commands that were sent to the instrument. I ran the “working” program using the 34980A in France from my NJ desk while Conrad in Colorado captured the commands. Then, Frederic in France ran the same program on his computer that did not work properly on the same 34980A while again Conrad captured the commands. After inspecting the commands from both program runs, Conrad spotted an error. For some reason, when Frederic in France ran the same program I ran in NJ, one of the commands in the program was generating an error within the 34980A. But now the question was how could the exact same program running on a computer in the US and on a computer in France produce different results?

Upon further inspection of the data captured by the 34980A’s remote traffic log, Conrad found the exact command that was causing the problem. The instrument error was caused by a numeric value being sent to the 34980A with a comma as the decimal separator (radix point) in the number instead of the decimal point that was expected by the 34980A. We then realized that the exact same program run on different computers produced different results due to the computers’ different “Regional and Language Options” setting. This was an unexpected and surprising result, but also easily remedied. I quickly changed my program to more strictly format the data I was sending to the 34980A to make it independent of the regional settings, emailed Frederic the new code, and it worked when run on either the US or French computer! Problem solved!!
Both Frederic and I were thrilled now that the demo was running perfectly. The remote troubleshooting ability afforded by the LXI instruments was instrumental in how we found the problem and how quickly we found it. Within 30 minutes of discovering a problem, we had three geographically dispersed engineers all collaborating on the issue in a way that would have been impossible without LXI. It was this experience that convinced me of the true power of LXI. Companies are becoming more geographically dispersed, travel costs are continuing to increase, and schedules are increasingly being compressed. The LXI benefit of remote troubleshooting reduces travel and speeds problem resolution clearly helping to mitigate many business challenges faced by engineering professionals today. I know I am convinced!

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