Our client had an existing data acquisition system, used for mechanical product validation testing, that had undergone many updates and patches for over 15 years. These updates and patches, performed by multiple developers, had rendered the software portion of the system somewhat unstable. Furthermore, the system hardware was based on NI SCXI, which was becoming obsolete. These issues prompted our client to migrate to an entirely new system.
New requirements for this upgrade included utilizing a PXI controller running NI Linux Real-Time, a RTOS, executing a LabVIEW RT application. The data acquisition software had to support a variable mix of signal conditioning modules in the PXI chassis. In addition, the data acquired from these signal conditioning modules needed to be synchronized within microseconds.
Viewpoint leveraged another application, developed for the client a few years prior, to harmonize the user interface and to reduce development effort. Most of the development time focused on support and configuration of the multiple module types and ensuring that the data synchronization functioned as required. The result was an ultra-flexible, portable, high-speed data acquisition software/hardware combination that can be used to acquire time-sensitive, synchronized data across multiple modules in a PXI chassis running a real-time operating system.
The upgraded system offers the following features:
- Highly configurable real-time data acquisition hardware/software solution based on LabVIEW RT and PXI hardware. Our client works closely with OEMs to assure compatibility and durability with their products, often going to the OEM’s test cells to collect performance data. The configurability in modules and channels affords the fastest possible setup at the OEM’s site which minimizes time and cost in the test cell.
- Configuration files stored in a SQL database format. Saving channel and module setups in SQL allows the test engineer to locate previous hardware and data acquisition configurations. The usual alternative is a bulk save of an entire system setup rather than using a more granular, and hence, more flexible approach afforded by using the database.
- Immediate test feedback through graphs and analog indicators, used to assure data quality before leaving the test cell.
- Data playback features after the data has been acquired, used for in-depth review of data after leaving the test cell.
- Data acquisition on the RTOS provides assurance that the acquisition will not be interrupted by network or other OS activities, which was occasionally an issue with the prior Windows-based application.
- Synchronization between signal conditioning modules ensures time-critical data taken on separate modules can be compared and analyzed.
The system consisted of custom LabVIEW RT software intended to run on an engineer’s laptop and the PXI real-time controller and a PXI chassis populated with a flexible assortment of NI signal conditioning modules (provided by the client).
The software used an object-oriented Actor-based architecture, which facilitates adding new signal conditioning modules and flexible communications between the host PC and the real-time controller.