Legacy Systems
Resolving the problems associated with obsolescence of Test and Measurement Instruments, Controllers, Operating Systems and Software
by Bill Watry and Les Hammer, Complete Test, INC.

     In many cases your test system has been on line for as many as 15 or more years. The system has been fully debugged and is serving its purpose well. The production line is running smoothly and everything is right with the world.
But, as time goes on you begin to realize that you are at risk. Many of the elements of the system are beyond life support and you are aware that support is rapidly disappearing. Parts and the instrument controllers are no longer available.    (Or are they?)    Personnel who understand the system have moved on. The operating system is obsolete. New hardware will not necessarily replace the old in functionality or in language compatibility. If the system should fail, how will you keep the production line moving?

What are your options?

Repair

     This is by far the cheapest solution in terms of capital layout, as long as you can afford the downtime should something break. Just leave the system as it is and wait until something breaks before fixing it. (If it ain’t broke, don’t fix it.) Complete Test is in touch with many manufacturers and equipment sources. Often we can repair your equipment even though the manufacturer will no longer support it. If you have a repair problem give us a call.

Lifetime buy – Spare Equipment

     If you cannot afford the risk of downtime, one solution may be to simply ensure that spare equipment is available in the event of failure.  A little bit of capital expense may be cheap insurance to keep your system running.  Now the solution will lie in the cost of stocking parts or components. Much of the legacy equipment is available through used equipment suppliers. Search the Internet! Complete Test can be enlisted to help locate legacy hardware.  You may be especially concerned with disk drives, as they contain valuable data, programs and operating systems.  Companies such as TAMS have replacement disks for use with old HP-UX and RMB systems.  Get one and back up your system now!

     The lifetime buy solution will work for some hardware, but some times key components are just not available because of limited production units in circulation. In that case a custom replacement design may be required. This may be expensive, but you can consider replicating the functionality with the right selection of T&M modules in a modern card cage system.

Replicate

     In some cases, a system is in operation, working smoothly and because of production demands, it is necessary to replicate the system. Or you may wish to replicate the system just to have a spare on hand in case one goes down.  Complete Test can assist you in this effort as well.

Update and Translate / Rewrite the Code

     If you really want to “bite the bullet”, this solution will enable you to choose modern technology, which will undoubtedly result in higher performance. What will it take?

     A complete update will require a significant investment. You will choose the latest computer, operating system, and programming language. On the measurement side, new Test and Measurement instruments should be evaluated for functionality to ensure that they will perform all the necessary functions and meet specifications.  But the equipment may only be a small part of the investment.  Look at the lines of code that you are running on the old system.  This code may have been developed over a period of years.  If the programming language is not being used anymore they will need to be replaced – at the same time investment that was required to develop the old code.  Figure 5 to 10 lines of code an hour to get an estimate of how much time will be required to develop the new code.  At $100/hour this can become a hefty bill!

     Once the hardware is in place, test system engineers must first understand the original program and then write or translate the test programs for the new system.  Most often, it is best to write the new test program “from scratch.”  A large part of the old program consisted of the user interface.  A line of text was written to the display as a prompt.  The user then typed a response and hit ENTER or RETURN to continue the program.  User interfaces don’t work that way anymore.  All the previous prompts need to be replaced with GUI elements.  Old programs may have spent a lot of code doing disk access.  New programs just open a file and start writing.  With so many things changing, translating the old code to new may take longer than writing the new from scratch.  But the programmer must know what needs to be tested.  If the test specifications are not documented, the old program may serve as a reference for those specifications.

     A serious problem probably lies in the limited number of people who will be able to understand and support the software and older operating systems. When update and rewrite is required, the most effective way to do the job is to enlist the services of experienced engineers who have had years of experience with legacy hardware and software. The engineers at Complete Test span the last 35 years of evolution in operating systems, languages, and Test and Measurement hardware and software.

     Which of these options you choose will undoubtedly be based on your risk assessment and just how much money you are willing to spend to solve the problem. The tough part of this decision is convincing yourself or management that a system that is running smoothly today is worthy of this kind of investment. Before you make that final decision, don’t forget to consider the cost to you if that system should fail tomorrow and shut down production or ground that plane.