Pickering Interfaces' Blog - Insights into Switching Technology

Considerations for Effective PXI Test System Matrix Maintenance

Posted by Bob Stasonis on Jan 19, 2021 10:39:23 AM

A goal of any manufacturing organization is to maximize the time that their test systems are operational. A test system that is down due to maintenance issues costs a company significant dollars in unrealized revenue. Switching systems, and in particular, matrices, are central to most automated test systems and rely on relays as the switching element. Relays are mechanical in nature, and as such, may fail over time for various reasons. This white paper explores these issues and discusses methodologies that can help shorten repair cycle time, in turn, sustaining and maximizing system uptime.

Considerations for effective PXI test system maintenance

Matrices allow for very flexible connection strategies between a single core set of test equipment and one or more DUTs (Devices Under Test). This approach saves the cost of duplicating test equipment; however, it also means that the switching matrix is placed in a central, potentially vulnerable position, where it may be subjected to abuse or accidents during use due to programming errors in development, wiring errors or unexpected DUT faults. Typical repair cycles can take up to 2- 4 weeks and can be extended when faults cannot be reproduced at the OEM.

The main factors that affect test system matrix reliability are the choice of relay used for the signal switching, and the conditions under which the relays must operate. The relays used in most matrices are mechanical devices whose lifetime is determined by the quality of their construction and moving parts, and the contact materials. A faulty relay can bring a production line to a halt; therefore, quick identification of the fault and subsequent repair is crucial in getting the system quickly back online, enabling product shipping to resume. High-quality EMRs (electro-mechanical relays) can have lifetimes in the order of 100 million operations under light load conditions. Still, instrument-grade reed relays have lifetimes in excess of one billion operations, and it is for this reason, as well as their smaller size, that reed relays are generally preferred.

Factors That Influence Relay Lifetimes

The conditions under which relays are operated impact the integrity of the contact materials. While in most cases it is best to cold switch a signal – i.e., perform the switching operation without any applied current or voltage stimulus – that’s not always possible. But it must be noted thathot switching’ – opening or closing a relay while it is carrying a signal – reduces relay life. Relays that hot switch signals run hotter than relays that cold switch and their contacts will erode much faster. Both of these factors – temperature and contact damage - will cause the relay to fail sooner. In general, vendors life-test relays with resistive sources and loads. In the real world, however, loads can be both inductive and capacitive, and these loads can shorten relay life to a greater extent than simple resistive loads.

It is not always obvious how much voltage or current is being hot switched by a relay. For example, if a relay is connecting a low impedance source to a high impedance load, it could be expected that the switched current will be relatively low. However, if the cabling or load has significant parasitic capacitance, there may be a high surge current through the relay when it closes as the source charges the effective capacitor.

A relay may also experience a high surge current when it connects a source to a capacitive load that is carrying a charge from a previous state. This might occur, for example, when a switching system reverses the polarity on a DUT, or if an earlier operation has left a charge on a high impedance load.

Switching systems are also typically capacitive at their terminals. If a switching matrix has a large number of closures on a single Y-axis to X connections, the resulting capacitance can create an extra load that can shorten relay life when hot switching.

Resistance in the cable wiring and the PCB tracks can help reduce the surge currents and therefore increase relay life, but this effect declines rapidly as the signal voltage increases.

High current or high-power inrushes are the most damaging and most frequent cause of contact damage. As well as inrushes due to charging capacitive loads, discharging capacitors can be an even more significant issue as the current is often only limited by the resistance of the reed switch and PCB tracks. Even capacitors charged to quite low voltages can cause current inrushes of tens of amps, and although they may be for microseconds only, they can cause damage to small reed switches.

Common Failure Mechanism in Relay Switching

The most common failure mechanisms for switching system relays used to hot switch signals are:

  • Welded contacts - usually caused by high inrush currents as the contacts are closed, creating molten or soft metal in the contact area - Figure 1.
  • Contacts having variable or intermittent contact resistance. This occurs particularly at low current levels because of the erosion of the contact materials. It may also be that the relay is reaching end of life.
  • Failure to close – caused by severe erosion of the contacts or the build-up of debris on the contacts (more an issue with EMRs as their contacts are exposed to air; reed relays have hermetically sealed contacts).

A fuller discussion of factors that influence the lifetime of relays can be found in our white paper entitled  ‘Avoiding failure modes in switch systems for test.’

Often, failures in test systems are caused by accident. For example, cabling and software errors can cause parts of the system to be connected that were never intended to be, resulting in shorts on power supplies or turning hot switch events into capacitive loads. The relay may withstand these accidents, but it could suffer partial damage to its contacts, which will shorten its operational life as the system is used and ages. Even when the system is operating correctly, an attempt to test a faulty DUT can force operation beyond the relay specification, stressing the switching system.

Fault Diagnostics

Historically, due to demands from customers (usually military or aerospace), platforms such as VXI have offered a self-test facility for the relays. However, the extent of test coverage provided could be patchy. Sometimes only the control system was tested and not the relay contacts (the most likely part to fail); other practices tested the relay contacts through hardware internal to the switch module, but it could not test the integrity of the connector. Products based on smaller footprint platforms, such as PXI, did not initially provide self-test. This gave rise to perhaps one of the most misguided approaches to managing the issue – ‘relay counting’. Here, the software counts how many times a relay has been operated so that the relay can be replaced when the number of operations reaches a given threshold. This method is deeply flawed for several reasons:

  • Relay life changes by three orders of magnitude according to the load present. The software has little or more commonly no knowledge of the load. It is merely a counting system.
  • It takes no account of the accidents that happen in systems, such as UUT failures, that shorten relay life.
  • Relays are subject to significant variations in lifetime by batch.

The consequence of this is that real switching systems can have a much shorter or much longer life than a relay counting system will indicate.

Diagnostic Test Self Test Tools

The good news is that the status of self-test is changing. Pickering now provides PXI matrix solutions, which include a built-in self-test facility called BIRST™ (Built-In Relay Self-Test), which addresses the shortcomings of the older self-test systems and the relay counting methods. BIRST is implemented as a very compact hardware addition to the PXI modules; the source/measure hardware is on-board and measurements are made through the matrix. It works in conjunction with a dedicated software application to electrically explore the matrix, measuring the resistance of each signal path with repeatability measured in a few milliohms. The user simply needs to disconnect the PXI module from the test system and then run the BIRST program. The test process is fast, each relay requiring just a few 10s of milliseconds to test fully. The software then displays the test results as a graphical representation of the matrix, highlighting any relays that are faulty and allowing the user to identify the physical position of each faulty device quickly. Every relay is checked; welded closed and stuck open relays are quickly identified.

BIRST Built In Relay Self Test Display

BIRST only identifies those relays which need attention for maintenance and avoids unnecessary disturbance and system downtime. The tool can identify relays with higher than expected path resistance, allowing users to change those relays before they fail. Through-hole relays are extensively used on Pickering’s switch matrix modules, allowing the user to self service the module with commonly available tools and get it back into service quickly. We encourage this practice: warranties are unaffected, and we even supplies spare relays on each switch module for the purpose

Our eBIRST external diagnostic test tools work similarly to BIRST but require an external test tool to be connected to the switch module under test. The relay testing source/measure hardware is contained within the tool, and an eBIRST software application exercises both the module and the connected tool and returns the relay test results and analysis.

While BIRST identifies faults within the matrix, it cannot verify the switch module’s front panel connector. So if a connector is damaged in any way, BIRST will not help. This is a key advantage that eBIRST brings: it allows the user to analyze the switching system right out to the external interface. The eBIRST test hardware can be connected directly to every individual relay on the switch module via the external connector, and this results in superior fault resolution compared to the BIRST tool, which tests relays using discrete matrix paths consisting of multiple switches. Another significant advantage is that eBIRST is available for any configuration of the switch module, not just matrices.

Like BIRST, eBIRST enables faulty relays to be identified so they can be replaced by the user on-site with minimal downtime. As with BIRST, we encourage this practice, and again, the warranty is unaffected.

The eBIRST tools are self-contained; only a USB2 port on a PC running Windows and the supplied application program are additionally required. The program uses a Test Definition File created for each switching module that defines how to test it. This enables users to test any of our switching systems that use mechanical relays with precious metal contacts (typically contacts with a rating of 2A or less) and also those incorporating solid-state relays. DC coupled RF systems using SMB connectors are also supported using test adapters. Each tool is generic—it will support DC-coupled switching systems that use multi-pin connectors on our PXI, PCI and LXI controlled switching systems. eBIRST also supports all-new generations of our BRIC matrix solutions, which now feature cross-point counts of over 9000 in a compact PXI module.

Signal Routing Software

Once the user has run BIRST or eBIRST diagnostic test tools and has discovered a faulty relay in a matrix, they may find that testing is still halted as they do not have a spare matrix (or relay) in stock. However, by using our Switch Path Manager (SPM) software, there may be a way to keep the tester functioning until a replacement is available.

Switch Path Manager simplifies signal routing through switching systems and speeds up the development of switching system software. Switch Path Manager supports our switching modules and the interconnection between them. Once a switching system model has been created, signal routing can be performed simply by defining the endpoints that are required to be connected—the ability to automate signal routing results in effective and easy switching system management.

In the event described above where a faulty matrix relay is discovered, but no replacement is immediately available, and repair by the user is also not an option, the operator can use the Exclude Endpoint feature within SPM to instruct the router not to use that path in its calculations. Figure 3 shows a matrix connecting a power supply to a DUT. The left-hand side shows the relay closures necessary to make the connections. However, if a relay fails along the Y2 axis, in SPM, a single command can be used to set up the router to avoid using Y2. This is shown on the right-hand side of the figure where we see that the switch path that originally used Y2 now uses Y3. Once the matrix has been repaired or replaced, the test engineer can remove the exclusion, and the program will run as before.

Pickering's Switch Path Manager Software Features

A thorough understanding of the factors that adversely affect the life of mechanical relays – the critical component in a switching matrix – will enable preventative maintenance based on proper operating procedures. This will reduce test system downtime and improve productivity. If a component does fail, new test procedures will allow the rapid detection of the fault, and expedite its repair, or provide an effective means to work around the problem.

If you have questions on your PXI test system maintenance - please feel free to contact us or visit our Support Knowledgebase for answers.

Topics: PXI, automated test system, test and measurement systems, Relay Reliability, Relays, test system maintenance

Simplifying Test Interconnect with Pickering’s Cable Design Tool

Posted by Bob Stasonis on Apr 6, 2020 5:34:31 PM
Simplify test interconnect

Correct interconnect products need to be selected once instruments and switching products have been chosen for a test set-up. This can be a complex process while checks are made, resulting in a significant investment in time, money, and in some cases, even exceeding the initial purchase cost of the devices.

The cable design for a test system is probably the last section of a test system development. And because proper cabling is critical for repeatability and accuracy, it needs care and expertise. Depending on the application, the test engineer needs to consider test specifications, including voltage, current, temperature, insertion losses, and more. From there, the engineer needs to determine the connections between the instrument and the Device Under Test (DUT), and then select connector types, backshells, wire length, and wire types. Unless the test engineer is an expert on cabling, researching wires and connectors can be a daunting task.

As a leader in test and measurement switching and simulation for over 30 years, we fully understand the importance of high performance and reliable interconnection between the component parts of a test system and DUT. That is why we established our own in-house connectivity division that manufactures a comprehensive range of 1200+ high-quality cable and connector solutions. There are times, however, when a standard cable assembly is not suitable, and there is a need for custom connectors and wire types or specific harness wiring. Pickering's free online Cable Design Tool (CDT) is a simple and efficient way of creating these custom cabling solutions.

Pickering's Cable Design Tool and completed cableThe cable itself can be drawn in a few clicks, choosing connectors, backshells and wires from a library. Linking them together is achieved manually by clicking on pins, or an auto-link option will link user-selectable groups of pins in 1-1 order. A third option is to use the CSV import, where the pinout with signal names can be prepared in an Excel sheet.

Currently, there are around 500 connectors and 400 types of wires and cables in the library (which is growing daily). These can be selected by many attributes, including pin count, connector type, rated voltage, conductor count, insulation type, conductor size and more. Many sophisticated functions, such as screening, sleeving and labels, bundling, and much more, can also be added. 

When the design is completed, the tool creates the full datasheet with all part numbers, lengths, labeling and pinout map for each path which can be downloaded in PDF format. Also, if the customer decides to work with Pickering, it can be used as build instructions for their production department. Otherwise, the customer is free to take the design and solicit other cable vendors.

Cable Design Tool data sheet

The tool is collaborative, enabling several people to work on a design, and once finished, the design is then sent to us to review. Our cable technicians can assist by suggesting cost-saving design changes and optimize the design for ease of manufacture by using stocked parts. Lead time is typically four to five weeks after receiving the order.

The main advantage offered by our connectivity division is the ability to provide precisely what you need. Our flexibility starts with the first point of inquiry. Our technicians receive cable drawings in many formats—AutoCAD, Visio documents, Excel pinouts, text descriptions, etc. They can analyze, design and manufacture complex custom cable harnesses. Our designers are there to help, whether modifying existing designs or designing new ones, our in-house production is flexible to cope with such demands and can manufacture in single quantities or high volume.

Start Using The Tool 

Take a look at our on-demand webinar "Simplifying Test Interconnect with Cable Design Tool" here >>

To learn more about cabling for your automated test system, take a look at our SwitchMate book, there is a whole section to help you understand it.

Cabling for your automated test system - Switchmate

Have questions or need more information? Please contact us here.

Topics: automated test system, software, Cables and Connectors

Automating Test Within Manufacturing Processes - White Paper

Posted by Kelly Porter on Apr 2, 2020 2:29:37 PM

 

whitepaper-cover-automating-test-within-maufacturing-processesIt is best practice when automating test within a manufacturing process to consider interconnection as an extension of the test instrument. In production, the interface between a device under test (DUT) and the test instruments will likely include a network of cabling, a signal distribution or switching subsystem, a connector panel, and device-specific adapters. In essence, all of the cabling, interfacing and switching should now be considered as an extension of the test instrument and must be allowed for when assessing the instrument’s capabilities.

There are always potential issues in production to keep in mind between a device under test (DUT) and the test instruments, focusing on how path resistance, line capacitance and insertion loss affect test results and what can be done to minimize their impact. Signal routing for test would be considered to be perfect if the path between the test instrument and the device under test was electrically ‘invisible’. Of course, this is asking the impossible. This is why test engineers need to take care of the whole measurement channel by considering everything between the instrument and the DUT, including cables, switching subsystems, connectors and mass interconnect products.

Selecting a flexible switching platform that can cover a range of application requirements and provide for future expansion provides a solid foundation for a test system design. You also want to keep in mind that in some cases, cables are supplied with switch modules, so they will have been designed to work with that module. This is why Pickering's modular switching portfolio provides maximum flexibility for system designs. Pickering also has a dedicated facility that produces cables and accessories to ensure that the performance of the switching module is not compromised by poor interconnections. 

Read the entire white paper here to learn more about potential issues in production between a device under test (DUT) and the test instruments, focusing on how path resistance, line capacitance and insertion loss affect test results and what can be done to minimize their impact. 

If you have questions or need more information on automating test within your manufacturing process – please reach out to one of our engineers here.

Topics: PXI, automated test system, test and measurement systems, Device Under Test, DUT, Cables and Connectors

Using Switch Matrices in Complex Test and Verification Installations

Posted by Kelly Porter on Oct 17, 2019 3:27:28 PM


Switch matrices are a flexible solution that should be part of your test strategy to automate complex test and verification whitepaper-image-Switch-Matrices-in-Complex-Test-and-Verificationsystems, especially in demanding industries such as aerospace, defense, automotive and semiconductor manufacturing. These matrices help accelerate test times over a manual process for test and facilitate reliable, repeatable and accurate results by eliminating error-prone manual intervention. The use of switch matrices can also help consolidate test processes in one space, rather than be distributed around several locations. Depending on the matrix type, it can also simplify the efforts to add additional test programs to the test system because of its ‘any test point to any instrument’ capability. There are limitations on simultaneous multipoint access as well as bandwidth. But proper matrix selection can shrink your test system and make it more flexible for today and into the future.

There are specific things you can think about to help you to understand how the use of switch matrices can save time and cost, reduce test area floor-space and improve reliability. These include what type of matrix to use whether it be crosspoint, tree multiplexer, RF and Microwave etc. You also want to understand how to configure a large matrix where software packages like Pickering’s signal routing software, Switch Path Manager (SPM), can simplify this programming effort. The maintenance of a switching system to avoid vulnerable positions and much more must also be included in your test strategy.

To learn more on this subject, check out our newest white paper here:  Using switch matrices in complex test and verification installations

For more information take a look at our updated SwitchMate Book.  If you have questions please contact us.

Topics: PXI, automated test system, test and measurement systems, PCI, Programmable Resistor, sensor simulation in test

The Challenges Surrounding Switching for Automated Test Systems

Posted by Kelly Porter on Oct 3, 2019 10:35:27 AM


challenges-surrounding-ate-whitepaper-image

Automated test systems rely on the performance, quality, and configuration of the signal switching that they are based on, yet the most significant challenge when considering switching for automated test systems may not be technical at all. Often we hear from customers that they feel switching is the last portion of their test integration strategy that needs to be considered. Switching is so simple, maybe even boring… how can anyone go wrong?

Think about the questions you should ask yourself surrounding switching for automated test systems such as:

  • What is a the importance of high-quality switching?
  • What are the differences between reed relays, electromechanical relays and solid-state relays?
  • What types of switching configurations are available?
  • Which cables, connectors and mass interconnect products should be included with my switch module?

The switching system is intrinsic to the success of the test process, so it’s important to understand the possibilities and limitations. However dull switching may seem, there are very many challenges to be considered, but the information is all here to help you. To learn more on this subject, check out our newest white paper here:  The challenges surrounding switching for automated test systems

To learn more, take a look at our updated SwitchMate Book or if you have questions please contact us.

Topics: PXI, automated test system, test and measurement systems, PCI, Programmable Resistor, sensor simulation in test

Understanding Programmable Resistors for Sensor Simulation in Test

Posted by Kim Otte on Oct 25, 2018 12:58:49 PM

If you think about it, sensors control much of our daily lives. Sensors ensure that the food in your refrigerator stays cold, programmable-resistors-image-for-whitepaper-lpcount your steps on a smartphone, and even protects you in an automobile accident. So many devices in our personal lives as well as in business and other markets contain sensors.

All these sensors add a layer of complexity to your test strategy, as you need to simulate them when testing the circuit board that makes decisions based on a sensor’s response. Since it is usually not practical to incorporate actual sensors into a test fixture, Pickering Interfaces has created external hardware that is designed to replace these sensors in a test program. In this paper, we will talk about sensor simulation and how to select these products. With Pickering’s history of more than 15 years designing programmable resistors, we have the expertise and product depth to play an important role in testing sensor-driven products.

Learn the right questions to ask when testing sensor-driven products.

  • What is a programmable resistor and why is it used for sensor simulation in test?
  • What are the different types and parameters for programmable resistors?
  • What if I need more accuracy in my test?
  • Are there different types of configurations I can use?

As you can see, there are many things to consider when selecting programmable resistor modules in test. It is undeniable that sensors are in virtually every application for electronics, making testing important, and sensor simulation can help you get there. We recommend you take a look at our latest whitepaper -

Understanding Programmable Resistors for Sensor Simulation in Test

To learn more, take a look at our web page: Programmable Resistor Solutions for Sensor Simulation or contact our simulation application engineers.

Topics: PXI, automated test system, test and measurement systems, PCI, Programmable Resistor, sensor simulation in test

Moving Your Test & Measurement System from VXI  to PXI : Not If, But When

Posted by Bob Stasonis on Oct 31, 2017 9:21:02 AM

In its day, VXI technology was a definite step forward. Built upon the modular VME computer bus, VME eXtensions for Instrumentation, or VXI, reduced the size and increased the performance of high-end test systems. Instead of bulky rack-and-stack systems, whose instruments were connected by the relatively slow GPIB interface, VXI systems featured modular instrumentation that plugged into a modified VMEbus that provided higher data transfer rates and real-time performance not possible with rack-and stack systems.

Moving from VXI switching to PXI switching

The VXIbus has served test & measurement engineers well, but it is more than 30 years old now, and it may be time to move to a more modern platform. Today, more test systems designers are choosing the PCI eXtensions for Instrumentation (PXI) platform when designing new modular test systems or replacing or updating existing test systems. Originally introduced in 1997 by National Instruments, PXI is now supported by nearly 70 companies working under the umbrella of the PXI Systems Alliance (PXISA), which publishes the PXI specification and ensures instrumentation interoperability.

PXI's main advantages: availability and lower cost

PXI's biggest advantage over VXI is product availability. In the nearly 30 years since VXI was introduced, the Consortium that manages the specification has gone from over 40 companies down to just eleven members. Even Pickering has dropped their VXI line due to key part obsolescence and reduced market requirements. A large number of the products that were available in VXI in the past are now obsolete and are often only available on the used market. That is not to say that VXI is no longer viable. In some specialized applications like Data Acquisition, there are VXI vendors producing new products. In other applications, VXI is mostly recommended for legacy applications and not for new designs.

A second reason to look closer at PXI for your test & measurement needs is that hardware costs are lower than VXI. Because PXI is based on the PCI bus, which is used in many personal computers, it can take advantage of the advances being made to serve the PC marketplace. Because many of the components used in PXI modules are also used for PCI modules, they cost less because so many more of them are made. This leads to overall reduced cost for PXI modules when compared to VXI modules. PXI systems typically cost one-half to one-third the cost of an equivalent VXI system.

Some of the other advantages that PXI enjoys over VXI include:

  • Data transfer. Standard PXI can transfer data that is 8, 16, 32, or 64 bits wide. VXI can only transfer data that's 8, 16, or 32 bits wide.
  • Data throughput. Because PXIe (Express version of PXI) systems can transfer data over high speed serial busses, the maximum throughput for PXI systems is higher than that for VXI systems. The maximum throughput for VXI systems is only 160 Mbytes/s, while the maximum throughput for PXIe systems is 12 Gbytes/s.
  • PXI modules are smaller than equivalent VXI modules. In fact, PXI systems have the smallest footprint of any open-architecture instrumentation system. This is a big advantage for PXI test systems because as test systems become more complex, test system developers need to cram more functionality into their test systems. PXI lets them do this while at the same time keeping test system size manageable.
  • Instrument availability. Aside from perhaps some very specialized instrumentation (an example would be Bustec with their specialized data acquisition systems), whatever you can buy in VXI, you can also buy in PXI. And, the trend is clear. There are fewer new VXI modules being developed than new PXI modules, and that will continue into the future as more designers specify PXI over VXI. In some applications, such as fault insertion during simulation, there are no VXI modules available. Also, because PXI is based on the CompactPCI specification, you can use CompactPCI boards in a PXI system.

Making the right choice

While the availability of PXI switching and instrumentation modules makes the choices relatively easy, there is the issue of migrating test programs from VXI to PXI, specifically in switching applications. The ability to replicate original test configurations to support legacy FRUs (Field Replaceable Units) is important to continue supporting older test programs while planning for future requirements.

To help ease this transition, we have developed PXI switching and simulation modules that closely match the operation of VXI switching modules from Racal, VTI Instruments, Agilent (Keysight), and other manufacturers. And, our policy of supporting our PXI Switching products for 15 to 20 years, or even longer, means that your next-generation test systems will have as long a life as their predecessors. An example of our VXI to PXI can be seen below.

Pickering's VXI to PXI switching cross-reference.

Our PXI modules listed in the table above are in many cases a close equivalent to the VXI modules. Because of the large PCB real estate of C-Size VXI modules, channel counts may be different, and specifications may not be exactly the same. Depending on your application, a different Pickering PXI module may be closer to your requirements than what is shown here. We also have cross-references to other manufacuturer's VXI switching.

Take a look at our VXI to PXI Cross-Reference here

Please contact our support team for more assistance in finding the correct module for your requirements.

Migration issues

While PXI is clearly the modular platform of choice when designing new test & measurement systems or upgrading existing systems, you may encounter some issues when doing so. One of them is module real estate. Clearly, a C-size VXI module has a lot more area to mount components, meaning that some VXI modules may have more features or functionality than a PXI module that you might choose to replace it. On the whole, however, VXI module designs are not as dense as today’s PXI module, so this is usually not an issue.

A related issue that you will have to address when migrating to PXI is cabling. VXI modules have a wider front panel (1.188-in.) than PXI modules (0.8-in.), meaning that many of the connectors used in VXI systems cannot be used in a PXI system. So, plan on building or buying new cables or buying adaptors.

If your instruments dissipate a lot of power, you may have cooling issues when migrating to a PXI system. The PXI cooling spec is less stringent than the VXI specifications, and generally, PXI chassis do not have the cooling power of VXI chassis. You may use multiple slots to achieve the necessary cooling.

Software is another area of concern. There is no easy way to migrate test programs. But, given the number of good test-development software packages available for the PC platform, this may not be as big an obstacle as it might appear.

Despite these drawbacks, if you're an automatic test system developer, the question is clear. It's not if, but when you should move to PXI-based systems from VXI. The answer is pretty clear, too. The answer is now.

Let us know your thoughts on moving from VXI to PXI.

Topics: PXI Switching, automated test system, test and measurement systems, VXI Switching

Pickering 1000+ PXI Module FAQ's

Posted by Kim Otte on Nov 5, 2014 12:06:00 PM

With over 25 years of signal switching and instrumentation experience, we have learned that when it comes to electronic test –"One Size Does Not Fit All" – that is why we now offer over 1000 PXI modules. 

Below are a list of frequently asked questions on why and how we offer such a large range.


Why does Pickering offer so many modules?

We entered the PXI market in 1998 with just a few modules—since then, primarily through customer demand, our PXI range has grown to over 1000 modules. This has been driven by a number of application requirements including:

  • Number of input and output channels
  • Voltage1000-pxi-modules
  • Power
  • Current
  • Bandwidth
  • Switch time
  • Switching life
  • Switching technology
    • Reed Relay
    • EMR
    • Solid State
    • MEMS
    • Microwave Relay
  • Crosstalk/isolation
  • Budget limitations
  • Low noise
  • Switching configuration and density

These requirements are so varied that test engineers demand a very wide and ever increasing range of solutions. “One size fits all” just doesn’t work in switching for Test & Measurement.

Take a look at our PXI Switching web page, on the left under product navigation it shows a product count for the number of modules available by main category and for each sub-category.

What types of PXI modules are produced by Pickering?

While PXI Switching & Programmable Resistors (for sensor emulation) are our main focus, we serve your electronic test requirements in other ways. Our PXI product line includes:

With so many modules, how can I find the exact one I need?

product reference maps

We have recently redesigned our website so you can quickly drill down to the exact module you need. We also have easy-to-use product reference maps with an overview of our entire range on one sheet.

In addition, we have highly experienced sales and applications people who understand switching and sensor emulation, and are just a phone call or email away

With so many modules, is delivery time compromised?

No. Typical PXI module delivery time is three weeks for almost all module types, often faster if required.

So how does Pickering offer quick delivery for such a large product range?

All module production processes take place in our two factories on flexible, demand-based manufacturing lines. We have complete control of the whole manufacturing process—we do not subcontract any process; everything is designed and manufactured in-house.

How can Pickering possibly offer long-term product support on such a large range?

As stated above, our in-house manufacturing gives us complete product control. From time to time, we update designs to improve performance and reliability while seamlessly managing any component obsolescence issues, all while preserving form and fit compatibility. Typical PXI module lifetime is in excess of 20 years, which is very important for many of our customers, especially in the Mil/Aerospace and Transportation markets.

How can you maintain and repair all these modules?

Pickering offers fast repair on a quick turnaround basis at very reasonable cost.

Built-in Relay Self-Test (BIRST)

In addition, Pickering has a strong background in diagnostics. Modules with our BIRST™ feature can quickly diagnose down to component level. For most other modules, we have our eBIRST™ Switching System Test Tools, this toolset connects externally to the module and can diagnose faults quickly. All of our PXI modules carry a three-year warranty which is unaffected if users choose to undertake their own relay replacement.

Why not just offer software-configurable modules instead of so many different variants?

We do offer several software-configurable modules for customers who require this flexibility. However, these have not proved popular due to the added cost of configuration relays and the inherent disadvantages of lower switching density, reduced AC performance and crosstalk/isolation compromises.

Are Pickering PXI modules compatible with “NI PXI”?

PXImate-practical-guide-to-PXIThis is a common question. Yes, of course, all of our PXI modules are 100% compatible with PXI products from all other vendors, including NI, Keysight and the other 60 members of the PXI Systems Alliance (PXISA).

Interested in learning more about the PXI Standard? Take a look at the article: "What is PXI" or get a copy of the 5th edition of our PXImate book. Click here to get your free copy!

What about Software?

Our module drivers support all popular software languages, including LabVIEW, Visual Studio, ATEeasy, LabWindows/CVI. We also support Real Time operating systems like Real Time LINUX as well as LabVIEW RT.

Can I use Pickering PXI Modules with other common buses?

Almost all of our PXI Modules can also be used in our LXI Ethernet chassis.

With such a big PXI range, where will I find suitable cabling and connectors?

We don’t leave you struggling to figure out your connectivity. We offer a similarly large range of connectivity options and in we have an on-line Cable Design Tool where you can design your own custom cable assemblies. 

We also have strong partnerships with the two mass interconnect companies, Mac Panel and VPC, who have 100’s of off-the-shelf as well as custom solutions.

Does Pickering really understand switching?

We are experts in switching technology. We have been designing and manufacturing modular switching systems since 1988, and our sister company, Pickering Electronics, has been designing and manufacturing instrumentation grade reed relays since 1968.

Switching expertise is in our DNA!

Have additional questions or comments? Please post your comment below or...

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Topics: PXI, PXI Switching, automated test system, test and measurement systems

LXI or PXI Switching for Automated Test Systems?

Posted by Kim Otte on Jul 16, 2013 4:42:00 PM

pickering lxi pxi switchingIs there a better platform to use for switching in automated test system? The answer is no, both the LXI and the PXI standards bring different advantages and disadvantages depending on what the user is trying to accomplish. 

For companies that embrace both the LXI and PXI standards for their switching systems, it is a question of what they decide is the appropriate soluition for their application.  PXI and LXI are sufficiently different - there will often be clear cases where one option is better for a particular solution than another.

LXI instruments are largely platform agnostic whereas PXI is very dependent on the PC architecture (and in many implementations, Windows). LXI devices do not have many mechanical or electrical constraints, but PXI products must conform to the PXI standard to benefit from the multivendor chassis platform. They also can have quite different data speed drivers.

In the illustration below you will see some of these differences:

PXI and LXI Comparison

To see more on the comparison of LXI and PXI switching for automated test systems, take a look at this article from the July issue of Evaluation Engineering: 
http://www.evaluationengineering.com/articles/201307/embracing-lxi-and-pxi-for-switching.php

You can also visit our knowledgebase for additional articles on Switching Platform selection: http://www.pickeringtest.com/kb/hardware-topics/switching-platform-selection

If you want additional information, please feel free to contact us by leaving a comment here or going to: http://www.pickeringtest.com/contact.html  

Do you prefer one standard over the other? Let us know your thoughts. 

Topics: PXI Switching, LXI Switching, automated test system