1. PXI and PXIe for Real-Time Applications
Murali Ravindran
PXI Product Manager
National Instruments

2. This picture shows Boeing’s phased array of 448 microphones and the eight PXI chassis that were distributed in a 250 ft. wide by 300 ft. long area and synchronized to within one degree at 93 kHz.

3. What is PXI? PXI = PCI eXtensions for Instrumentation
Open specification governed by the PXI Systems Alliance (PXISA) and introduced in 1997
PC-based platform optimized for test, measurement, and control
PCI electrical-bus with the rugged, modular, Eurocard mechanical packaging of CompactPCI
Advanced timing and synchronization features
PXI (PCI eXtensions for Instrumentation) is an open specification governed by the PXI Systems Alliance (PXISA) that defines a rugged, CompactPCI-based platform optimized for test, measurement, and control. PXI combines PCI electrical-bus features with the rugged, modular, Eurocard packaging of CompactPCI and adds specialized synchronization buses. This makes it both a high-performance and low-cost deployment platform for measurement and automation systems. These systems serve applications such as manufacturing test, military and aerospace, machine monitoring, automotive, and industrial test.

4. PXI Combines Standard Technologies
PXI Backplane
PCI bus
Timing and
Synchronization
Controller
Embedded PC or remote PC / laptop interface
Runs all standard software
Chassis
PXI systems are comprised of three basic components – chassis (which includes the PXI backplane), controller, and peripheral modules. The chassis provides the rugged and modular packaging for the system. Chassis range in size from 4 to 26 slots. The chassis contains the high-performance PXI backplane, which includes the PCI bus and timing and synchronization buses. All PXI systems include a controller. Controller options include remote control from standard desktop and laptop PCs, 1U rackmount controllers, and high-performance embedded controllers. Because PXI embedded controllers are built using standard PC components, they run standard operating systems, such as Windows XP, and applications, such as Microsoft Excel. Over 1,000 different peripheral modules are available from the 70+ members of the PXISA. Modules are available for instrumentation, data acquisition, control, interfacing to buses, etc.
Peripheral Modules

5. Industry Bus Performance
10000
1000
100 10 1
0.1
Good
Better
Best
PCI/PXI (32/33)
Max Bandwidth (MB/s)
Gigabit Ethernet
USB 2.0
IEEE 1394a
VME/VXI
Fast Ethernet
GPIB (HS 488)
This graph shows various busses and their associated bandwidth and latency. Latency or the minimum time to do a single transaction is decreasing along the x axis and bandwidth is increasing along the y axis. To highlight popular industry busses, you can see where GPIB, USB 2.0 and the Ethernet families sit relative to each other.
PXI uses PCI communication which is the highest-bandwidth and lowest-latency bus on this chart, providing up to 132 MB/s.
In addition to bus throughput performance, PXI has timing and triggering lines for module synchronization…
USB 1.1
GPIB (488.1)
Approximate Latency (μs)

6. Leveraging PCI Express
Data bus for PXI
Data bus for PXI Express
PCI
132 MB/s
Shared Parallel Bus
PCI Express
250 MB/s to 4 GB/s
Independent Serial Bus
Modules up to 1 GB/s
Host up to 6 GB/s (2-link)
4 GB/s (4-link)
The PXI Express spec allows for a maximum of 4 (max link width x4) links for a total of x16 to the host OR 2 (max link width of one x16 and one x8) for a total of x24 to the host.

7. Industry Bus Performance
10000
1000
100 10 1
0.1
PCI / PXI Express (x4)
Good
Better
Best
PCI/PXI (32/33)
Max Bandwidth (MB/s)
Gigabit Ethernet
USB 2.0
IEEE 1394a
VME/VXI
Fast Ethernet
GPIB (HS 488)
This is the same graph from the “What is PXI” section that shows various busses and their associated bandwidth and latency. Latency or the minimum time to do a single transaction is decreasing along the x axis and bandwidth is increasing along the y axis.
A “by four” PCI express link has the lowest latency and furthers the bandwidth lead over other busses. A x4 link can provide up to 1 GB of data in each direction
USB 1.1
GPIB (488.1)
Approximate Latency (μs)

8. PXI Timing and Triggering
Star Trigger Bus
10 MHz
CLK
Controller
System
Local Bus
Peripheral
Peripheral
Peripheral
Peripheral
Timing Slot
System
PXI Trigger Bus 0..7
The additional Timing and triggering features of PXI allow modules to synchronize themselves in a variety of ways. The first feature is a 10 MHz system clock that is provided to each peripheral module. Modules can synchronize to this clock to achieve synchronization.
The second feature is the PXI Trigger bus. This parallel bus provides 8 trigger lines that can be used to send triggers or signals between devices. Because the bus is a parallel bus, skew can be introduced by bus load and trace-length mismatch. To provide a method for limited-skew synchronization, PXI also incorporates..
A Star Trigger bus. This single-source, single destination bus can be sourced from the system timing slot and each trace is matched length to ensure minimal skew between devices.
The last synchronization bus is the Local Bus. This bus provides 13 to the left and 13 lines to the right peripheral module.
PXI_CLK10
10MHz point to point
<1ns skew
PXI_STAR
Point to point
<1ns skew
PXI_TRIG
8-line parallel trigger lines

9. Additional Features in PXIe
Supplied Power and Cooling Increase
Geographical Addressing
Timing and Synchronization
100 MHz differential clock
Differential Star Triggers
Available power to modules has increased to 140 W for the system controller and 30 W for a peripheral module to enable higher-performance products.
Geographical addressing allows for software to read the slot position of a PXI Express module independent of the driver being used for the device.
Additional timing and triggering signals improve upon the first revision of PXI (PXI-1). To look at these timing and triggering signals in greater detail…

10. PXI Trigger Bus (8 TTL Triggers)
100 MHz
Differential CLK
PXI Express
Star
Trigger
10 MHz
CLK
PXI Express
Controller
System
PXI Express
Peripheral
Hybrid
PXI Express
Peripheral
Hybrid
PXI Express
Peripheral
Hybrid
PXI Express
Timing Slot
System
Peripheral
PXI
PXI Express adds additional signals to the PXI-1 specification discussed in the first section. The diagram above is a PXI Express extension of the PXI diagram used in the first section. Note that all slots are PXI Express capable but the rightmost slot. All PXI-1 timing and triggering features but local bus are still distributed to every peripheral slot.
In this diagram, PXI Express additions to PXI-1 timing and triggering features are illustrated in orange.
The first addition is a 100MHz differential clock. As with other PXI Express timing and triggering features, the clock is only routed to PXI Express slots.
PXI Trigger Bus (8 TTL Triggers)

11. Comparing PXIe_CLK100 and PXI_CLK10
PXI_CLK10 preserves compatibility with PXI modules
PXI_CLK10 is synchronous to PXIe_CLK100
Specifications comparison
PXIe_CLK100
PXI_CLK10
Frequency
100 MHz
10 MHz
Logic Family
LVPECL, Diff
TTL, SE
Freq. Accuracy
±100 ppm or better
Skew
≤ 200 ps
≤ 1 ns
Two important details to note are that PXI_Clk10 is synchronous to PXIe_CLK100 so devices that use either PXI_CLK10 or PXIe_CLK100 as a reference clock are synchronized
Additionally, the skew of the new clock has been improved from a module-to-module skew of <= 1ns to < or = 200ps to minimize skew between peripheral devices.

12. PXI Trigger Bus (8 TTL Triggers)
100 MHz
Differential CLK
PXI Express
Star
Trigger
SYNC Control
SYNC100
10 MHz
CLK
PXI Express
Controller
System
PXI Express
Peripheral
Hybrid
PXI Express
Peripheral
Hybrid
PXI Express
Peripheral
Hybrid
PXI Express
Timing Slot
System
Peripheral
PXI-1
Another addition in PXIe is the Sync100 signal. This signal can be controlled by the system timing module…
PXI Trigger Bus (8 TTL Triggers)

13. PXIe_SYNC100 Delivered to each PXIe peripheral slot
Differential LVPECL signal
10ns pulse coordinated to PXI_CLK10
The Sync100 signal is a differential signal delivered to each PXIe peripheral slot. Sync100 provides a 10ns pulse that is coordinated with the rising edge of PXI_CLK10. As you can see from the timing diagram, a 10ns pulse on Sync100 immediately precedes a rising edge of PXI_CLK10.

14. PXI Trigger Bus (8 TTL Triggers)
100 MHz
Differential CLK
PXI Express
Star
Trigger
SYNC Control
SYNC100
10 MHz
CLK
PXI Express
Controller
System
PXI Express
Peripheral
Hybrid
PXI Express
Peripheral
Hybrid
PXI Express
Peripheral
Hybrid
PXI Express
Timing Slot
System
Peripheral
PXI-1
Differential Star
Triggers
To minimize skew between peripheral device, the PXI-1 specification provides a point-to-point Star trigger for matched trace-length signaling from the system timing slot. PXI Express adds three Differential Star triggers to the specification to allow for higher frequency signaling with less jitter.
PXI Trigger Bus (8 TTL Triggers)

15. Differential Star Triggers
PXIe_DSTARA, PXIe_DSTARB, PXIe_DSTARC
Differential, point-to-point connections
Matched length to within 150ps
PXIe Peripheral Slots and the System Timing Slot
Allows for increased clock frequency distribution
The three PXI Express star triggers are named DSTAR a, b and c. These are matched-length differential point-to-point connections between the system timing module and PXI Express peripheral modules

16. Integrating PCI Express into the PXI Backplane
Up to 2 GB/s dedicated bandwidth per slot
Enhanced synchronization capabilities
100 MHz differential clock, differential triggering
Backwards compatibility
Complete software compatibility
Hybrid slot definition - install modules with either PCI or PCI Express signaling in a single slot
Differential triggering gives a cleaner signal so better accuracy
The next step is to integrate the PCI Express bus into the PXI backplane. The PXI Express backplane integrates PCI Express while still preserving compatibility with current PXI modules, users benefit from increasing bandwidth while maintaining backward compatibility with existing systems. PXI Express specifies hybrid slots to deliver signals for both PCI and PCI Express. With PCI Express electrical lines connecting the system slot controller to the hybrid slots of the backplane, PXI Express provides a high bandwidth path from the controller to backplane slots. Using an inexpensive PCI Express-to-PCI bridge, PXI Express provides PCI signaling to all PXI and PXI Express slots to ensure compatibility with PXI modules on the backplane. With the ability to support up to a x16 PCI Express link in addition to a x8 link, the system controller slot provides a total of 6 GB/s bandwidth to the PXI Express backplane, representing more than a 45X improvement in PXI backplane throughput.

17. Real Time Architectures on PXI
Non-Deterministic
Deterministic

18. HW-Timed I/O Non-Deterministic Deterministic Controller I/O Element
Non-RT OS
Windows, Linux, etc.
FIFO
Data Bus
Clock
Software Task 1
DAC

19. Clocked I/O Non-Deterministic Deterministic PXI System Controller
PXI Timing Backplane
I/O Element
Non-RT OS
Windows, Linux, etc.
Software Task 1
DAC
DAC
ADC

20. RTOS Non-Deterministic Deterministic PXI System Controller
PXI Timing Backplane
I/O Element
RTOS
LVRT, RT Linux
DAC
Software Task 1
DAC
ADC

21. On-Board Processing Non-Deterministic Deterministic PXI System
Controller
PXI Timing Backplane
I/O Element
Non-RT OS
Windows, Linux, etc.
Smart I/O Element “RIO”
FPGA
Task2
Software Task 1
DAC
ADC
ADC

22. This picture shows Boeing’s phased array of 448 microphones and the eight PXI chassis that were distributed in a 250 ft. wide by 300 ft. long area and synchronized to within one degree at 93 kHz.
PXI Chassis

23. Partial PXISA Member List
Here is a partial list of the PXISA membership. A complete list is available at
Complete list at pxisa.org

24. PXI – The Fastest Growing Standard in Test
Actual
Forecast
23% CAGR forecast for 2006 – 2012
Source: World VXI & PXI Test Equipment Markets, Frost & Sullivan, September 2006
Number of Systems Per Year
More than 1,500 PXI Products Available!

25. Future PXI Growth Vs. Other Areas of T&M
Growth Through 2011
Oscilloscopes 2.9%
Multimeters %
Overall T&M %
PXI %
Electronic Design
2006 Technology Forecast, 1/12/2006

26. PXI Industry Adoption – Electronics Industry
Electronic Business 300 – The Rankings
9 of the 10 top Contract Manufacturers use PXI
17 of the 20 top Electronic Businesses use PXI
PXI has seen wide industry adoption, which is especially evident when looking at the top electronics industry businesses and contract electronic manufacturers. In fact, PXI is used by 9 of the top 10 contract manufacturers based on data from Electronics Business 9/1/04 and National Instruments PXI usage study. Top 10 contract manufacturers include: Flextronics, Solectron, Sanmina-SCI, Celestica, Jabil Circuits, Elcoteq, Venture, Benchmark Electronics, Universal Scientific Industrial, and Plexus.
In addition, PXI is used by 17 of the top 20 Electronics Businesses based on data from Electronics Business 8/1/05 and National Instruments PXI usage study.
Electronics Businesses magazine can be found online at
Source (Rankings): Electronic Business, August 2005
Source (PXI Use): National Instruments, June 2005

27. Real-Time Measurements for Tokamak Control with Multicore PC and PXI Systems
Dell 2 Quad Core server connected to PXI-1045 (18 slots) by MXI-Express 2-port MB/s
Fusion
DAQ system + magnetic probes
Magnetic equilibrium/Grad-Shafranov
Function parameterisation
Multicore processing application

28. Harvard Research Group Uses NI LabVIEW and PXI to Study Nanowire Growth
Application: Developing a highly flexible and compact lock-in amplifier
Challenge: Creating a virtual, high-channel-count, lock-in amplifier for nanotechnology research.
Products: LabVIEW, Modular Instruments, PXI/CompactPCI
Key Benefit: Flexibility to combine multiple PXI modules and instruments into one project.
Harvard Research Group Uses NI LabVIEW and PXI to Study Nanowire Growth
“The system provides improved cost, smaller dimensions, and more flexibility than its traditional counterpart. NI: $93,100 USD, Traditional: $512,000 USD”
Harvard Research Group Uses NI LabVIEW and PXI to Study Nanowire Growth 28 28

29. Case Study – Freightliner Selects National Instruments LabVIEW and PXI to Verify Truck Assembly
Freightliner selected LabVIEW and PXI to verify electrical assembly on its new line of heavy-duty trucks.
Freightliner engineers integrated electrical test, machine vision and physical measurements into a system that not only ensures high-quality vehicles but also instructs operators on the correct assembly process.
“We set out to design a high-performance test system that would give us the flexibility of a completely off-the-shelf solution. This system delivers on both requirements and the successful development is reflective of the valuable relationships Freightliner enjoys with both external and internal resources.”
What: Freightliner is using LabVIEW and PXI to test it’s new line of trucks.
Challenge: Developing a system that combines machine vision, electrical test and physical measurements into a single production test system.
Solution: Using LabVIEW and PXI to design an open, off-the-shelf system that can be easily expanded for future applications.
Why: Freightliner is the largest heavy-duty truck manufacturer in North America and a leading producer of medium-duty trucks and specialized commercial vehicles.
This application supports the ETT campaign.
Additional Information: Freightliner is a DaimlerChrysler company. The integrator, Wineman Technology, pitched this application to Freightliner at a NITS event and built the prototype in his house.
“Using machine vision to verify the assembly of the fuse box goes beyond the industry standard of validating serial fuse continuity,” said Darryn La Zar, vice president of Sales and Marketing at Wineman Technology. “For instance, this solution can detect if a 30 A fuse is in a 5 A slot, which was not possible before.”

30. Case Study - PSA Peugeot Citroën Simulates Automotive Environments with NI LabWindows™/CVI and PXI
PSA is Europe’s second-leading automotive manufacturer, with strong growth in Latin America and China
The company developed a modular test system for prototype vehicles that reduced functional test by half over traditional instruments
“By using an approach based on National Instruments LabVIEW software, integrating our simulation models with real-world I/O, we cut development time nearly in half, to 14 days. This is a key element to consider when reducing vehicle time-to-market.”
What: One of Europe’s largest automobile manufacturers is using LabWindows too validate engine control without a prototype.
Challenge:
Performing functional validations without a prototype vehicle, but with similar electronic topology.
Solution:
Designing a low-cost, high-performance, and simple modular system using PXI hardware and National Instruments LabWindows/CVI application development environment.
Why: PSA had to quickly implement validation tools with an industry-standard programming software that was easy to maintain and had a flexible configuration. It was also necessary to find simple, low-cost, high-performance tools.
This supports the VI campaign.
Additional Information: PSA chose a modular PXI system, which included an 8-slot chassis connected to isolated and conditioned signals to protect the NI modules. The chassis, which can be driven by an external PC via the National Instruments PXI-8330 or embedded in an NI PXI-8187 controller, contains a PXI-6040 multifunction data acquisition module; the PXI-6713 and PXI-6704 analog output modules; the PXI-6602, PXI-6624, and PXI-6527/28 digital I/O modules; and two PXI-8461 CAN interface modules.
In some configurations, the application handles up to 18 analog inputs, 32 analog outputs, 24 digital inputs, 24 digital outputs, 10 counter inputs, and 4 counter outputs.

31. Testing a Multitone Transceiver with PXI and NI LabVIEW
Application: Use the NI PXI signal generation and digitizer hardware and the National Instruments LabVIEW Real-Time Module to provide hardware and software platforms for the physical layer of a real-time communications system.
Challenge: Prototype the physical layer of a communications systems to rapidly evaluate system design tradeoffs.
Products: LabVIEW RT, PXI and Modular Instruments
Key Benefit: Time savings, easy-to-make GUI
“The LabVIEW Real-Time Module and the PXI hardware allowed us to avoid time-consuming embedded programming and analog circuit design.”
Submitted paperr 31 31