Developing a Hypersonic Wind Tunnel Control, Networking, and DAQ System Using LabVIEW and PXI

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"We used NI PXI and SCXI hardware with LabVIEW software to develop a complex, accurate, and fast DAQ and control system for a wind tunnel with an almost 70 percent time savings in software development."

- Manoj K. Singh, Vikram Sarabhai Space Centre (VSSC)

The Challenge:
Configuring control and DAQ hardware from a single workstation combined with software for data logging, data processing, and graphical display for wind tunnel DAQ.

The Solution:
Using dual-redundant distributed NI PXI and SCXI hardware for DAQ and NI LabVIEW for data processing and graphical display.

Manoj K. Singh - Vikram Sarabhai Space Centre (VSSC)
P G. Raveendran - Vikram Sarabhai Space Centre (VSSC)
Vargeese Jacob - Vikram Sarabhai Space Centre (VSSC)
S Pandian -

Our team from the AERO department at VSSC Trivandrum (ISRO) used NI PXI and SCXI to develop a hardware configuration and used LabVIEW software for the required control and DAQ of a new 1 m hypersonic wind tunnel.

In any aerodynamic design, the wind tunnel requires high pressure, a high vacuum, high temperatures, and a high volume of air with a reliable, accurate DAQ system. It also requires a process control system with graphical monitoring. The system processes large amounts of data measured from the sensors with graphical representation and requires database management. Most software tools for supervisory control and data acquisition (SCADA) and DAQ are costly, require software development knowledge, and support only particular types of hardware.

System Description

Process control involves both digital and analog control. We used hot standby hardware based on a programmable logic controller (PLC) for process control and NI-based hardware for DAQ. We connected 14 real-time PXI modules (seven prime and seven redundant), four PLCs, four consoles, and two redundant SCADA servers for control and DAQ. We also used more than 400 types of sensors. Each DAQ module featured SCXI technology for signal conditioning. We developed the software, which involved SCADA, real-time PXI hardware, consoles, real-time channel display, and networking, using LabVIEW.

Each DAQ station incorporated real-time DAQ software that we developed using the LabVIEW Real-Time Module. The DAQ software configured the PXI and SCXI channels. We could set configuration parameters such as log rates, sampling rates, gain, and channel bandwidth from the SCADA station using the graphical interface. DAQ software also updated its channel data at a rate of 500 ms to the network. At the end of the test, the system transferred all data to the SCADA station (see Figure 1).

The SCADA station was the heart of the control and DAQ system for the wind tunnel process. It provided a GUI for the operator and contains more than 20 GUI pages. The SCADA station performs the following functions:

  • Sends configuration data to the DAQ station
  • Monitors the process parameters of the control system
  • Provides an interface between DAQ and the PLC
  • Provides a GUI interface for the operator
  • Collects data from DAQ stations at the end of the test
  • Performs offline and online data processing
  • Manages the database
  • Includes a Modbus master for networking

We developed the entire SCADA software using LabVIEW (see Figure 2). The consoles were an active graphical representation of the subsystems. The system used four consoles for process monitoring for the wind tunnel system. Each console front end and back end was developed using LabVIEW, and we uploaded the .exe version on the console system (see figures 3 and 4).

Networking the different types of hardware, such as the PLC, real-time PXI hardware, a SCADA system, and consoles, was the backbone of the system. We used the Modbus master slave configuration to share data between the SCADA system and the PLC. The same configuration was used for data communication between DAQ stations and the SCADA system. The SCADA system always behaved as the Modbus master and other devices as the slaves. The consoles took data from the DAQ stations via the SCADA system. Communication between the SCADA system and the consoles was implemented through NI-bound shared variables. Using the LabVIEW Datalogging and Supervisory Control Module, we quickly developed the entire networking software with little software development knowledge (see Figure 5).

Quick and Easy Development

We used NI PXI and SCXI hardware with LabVIEW software to develop a complex, accurate, and fast DAQ and control system for a wind tunnel with an almost 70 percent time savings in software development.

Author Information:
Manoj K. Singh
Vikram Sarabhai Space Centre (VSSC)
Tel: +91 471 2562881

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