Calibration and Specification Considerations When Using Modular Instrumentation

Abstract

Calibration and Specification Considerations When Using Modular Instrumentation. Modular instrumentation, such as PXI or AXIe modular instruments, offers significant configuration flexibility, plus interchangeability, speed, and size advantages when it comes to deploying measurement systems. However, the architecture that enables these advantages also presents unique challenges when calibrating modular instruments. Calibration often occurs outside of the use environment. For modular instrumentation, this may mean performing calibration on a module with a different chassis and its related electronics. Additionally, the module’s ambient environmental conditions depend upon chassis fan speed, the use of slot blockers and EMC filler panels and the presence of other modules. The operating software and CPU for modular instruments are contained outside the module in an external computer, which may not travel with the module for calibration. Modular instrumentation may require multiple modules configured together to provide measurement capability. This may require calibration on the set of modules as a system or, a method to relate system level performance to the calibrated performance of individual modules. These issues affect both the calibration and the calibration report and influence how manufacturers may define specifications for modular instrumentation. This paper examines these issues in detail and considers both in situ calibration and calibration performed outside the use environment. Recommended is information to be included on the measurement report that is unique to calibration of modular instrumentation. Addressed are the requirements for assuring the ability to make traceable measurements using calibrated modular instrumentation.