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NI Legacy System Case Study: SALT (South African Large Telescope)

NI Legacy System Case Study: SALT (South African Large Telescope)


The South African Large Telescope (SALT) is a flagship astronomical instrument, known for its critical role in advancing our understanding of the universe. However, like any sophisticated piece of technology, it requires precise and reliable components to function optimally. This case study highlights the challenges faced by the SALT team in maintaining their legacy telescope positioning system and how Extend Test provided a vital solution.


The legacy telescope positioning system at SALT utilized the NI PXI-1000B chassis, with a PXI-8335 MXI interface, PXI-6071E data acquisition module, and the PXI-7334 motion controller, all of which have since reached End of Life (EOL). These components were crucial for the accurate positioning of the telescope, allowing it to capture high-quality astronomical data.


The SALT team began experiencing intermittent error messages in their software, disrupting the telescope's operation at random intervals. LabVIEW would return “Read Data Buffer” errors, which were initially suspected to be caused by a malfunctioning PXI board.  However, there was no way for the SALT team to verify this suspicion, as they did not have access to other PXI components to do swap tests with.


To address these issues, the SALT team sought assistance from Extend Test. The following steps were taken:

  1. Problem Reproduction: Extend Test guided the team to a LabVIEW example to reproduce the error messages and isolate the error. This step was crucial in isolating the issue and understanding the specific conditions under which the errors occurred.  After conducting this test, the symptoms still persisted, further confirming that this might be a hardware error since software causes had been minimized.
  2. Visual InspectionUpon inspection, suspected corrosion of the PXI module was found, along with discoloration on the PCB. The corrosion had compromised its functionality, necessitating a replacement.
  3. Replacement Parts: Extend Test supplied the SALT team with replacement PXI parts. Upon switching to another PXI chassis, the symptoms did not occur anymore.  These components were sourced to ensure compatibility and reliability, thereby restoring the functionality of the telescope positioning system.

Testing replacement parts at Extend Test labs before shipping to customer


With the new PXI parts installed, the error messages ceased, and the telescope's operation returned to normal. Although the root cause of the original symptoms was not known, the replacement parts provided by Extend Test not only resolved the immediate issue but also offered a sustainable solution for maintaining the legacy system.


This case study highlights the importance of reliable hardware components in legacy systems.  Extend Test's expertise in sourcing and supplying replacement parts proved invaluable, ensuring the continued operation of this critical astronomical instrument. For organizations managing legacy test and measurement systems, Extend Test offers a proven solution for overcoming hardware-related challenges.

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