C&H Technologies

M228 1MSPS Aperture A/D (Part 2)

2009-05-04T14:14:00.000-07:00

It has been three long months since posting the first in this three part series on the new M228 Aperture A/D M-Module. Those three months have been filled with a lot of hard work on, among other things, improving and finalizing the EM405-8 Scripting Utilities. All the while, I haven't forgot about the M228 and would like to continue the discussion with a description of the unique aperture features of this module.

As I touched upon in the first post of this series, the aperture feature controls the M228's decisions on whether or not to store an A/D sample. The M228 performs an A/D conversion at every tick of the sample clock (up to 1 Mega Samples per Second) but it does not necessarily store every A/D conversion into the 32 Meg Sample FIFO. Of course, using the force store feature, the module can be configured to store every conversion, but if that was the only mode of operation, this article would be over when in fact, we are just getting started. The decision by the hardware of whether or not to store a particular sample is based on the current A/D value (the one which the decision is to be made on), the last stored A/D value, the settings of the aperture window(s) and the aperture mode. As shown in the figure below, using the aperture feature can greatly reduce the amount of data required to be stored, parsed, and transferred across the system bus (note: the image uses aperture mode 0 discussed below).

(click image to zoom in)

The M228 has two aperture windows. Each aperture window has a high and a low value. The meaning of each value and how the values are used in the decision making process depends on the aperture mode. They will be discussed for each mode below. In some aperture modes only one aperture window is used, in other modes both aperture windows are used. I can't describe much else without getting into the various modes...so lets get to them. In order to keep this article a reasonable length, I will refrain from using examples for each mode and let your imagination do the job.

Aperture Mode 0 - “Store if outside selected aperture window”

Aperture Mode 0 allows the user to store data only if it changes more than a specified amount from the last stored value. For instance, if only signal changes greater than 200mV in the positive direction and 100mV in the negative direction are important, the user can specify Aperture Mode 0 and set Aperture High to 200mV and Aperture Low to 100mV. The A/D reading will be stored if the value is greater than the last stored value plus the Aperture High value or it is less than the last stored value minus the Aperture Low value. In this mode, only positive aperture values can be specified. Since the A/D value is always compared against the last stored value, this mode can be visualized as a window that floats with the signal. Each time a value is stored, the window is repositioned to this level. In this mode, aperture high and low setting of zero causes the M228 to store all.

Aperture Mode 1 - “Store once outside selected absolute window A and outside of aperture window B”

Aperture Mode 1 allows the user to start storing data once the signal level is outside of a specified absolute window, in effect setting a trigger level. For example, if the user would like to start storing data if the signal rises above 1V, Aperture High A would be set to 1V and Aperture Low A would be set to a large negative value. Operation begins with Aperture Set A. If the signal level is outside the specified absolute aperture window the logic stores the value and switches to Aperture Set B. Operation continues with Aperture Set B acting exactly like aperture mode 0 until the FIFO is reset.

Aperture Mode 2 - “Store if outside absolute window A and outside of aperture window B”

Aperture Mode 2 allows the user to only store data if the signal level is outside of a specified absolute window and the delta from the last value stored is greater than some amount. The mode is similar to Aperture Mode 1, except data is only stored if it is outside of the absolute window specified by Aperture Set A. In other words, in contrast to Aperture Mode 1, if the signal returns inside the absolute window, storage will cease until it leaves the absolute window again. Outside of the absolute window, Aperture set B is used exactly as in Aperture Mode 0 and 1.

Aperture Mode 3 - “Store once inside selected absolute window A and outside of aperture window B”
Aperture Mode 3 allows the user to start storing data once the signal level falls inside of a specified window. This mode is very similar to Aperture Mode 1, except data storage will begin if the signal falls or rises to be within a specified window.

Aperture Mode 4 - “Store if inside absolute window A and outside of aperture window B”

Aperture Mode 4 allows the user to only store data if the signal level is inside of a specified window level. This mode is very similar to Aperture Mode 2, except data storage is stored only if the signal is inside a specified window.

Aperture Mode 5 - “Store if outside both absolute window A and B”

Aperture Mode 5 allows the user to store all data that is outside of two absolute windows. For example, if data storage is not important when the signal is between -2V and -3V or between +4V and +8V, aperture set A would be set to -2V and -3V and aperture set B would be set to +8V and +4V. Data will be stored on every sample clock that the data level is not within one of the specified windows.

Aperture Mode 6 - “Store if inside either absolute window A and B”

Aperture Mode 6 allows the user to store all data that is inside of either absolute window. This mode is very similar to Aperture Mode 5, except data is stored only if it is inside either window.

Hopefully, from the above aperture mode descriptions, one can draw enough information to realize the advantages of the data extraction techniques of the M228 and imagine their use in a real world application. The M228 is the most powerful instrument in our transient data acquisition offering. You can download a brochure of our transient data acquisition solutions here.

The final part of the M228 series of articles will discuss the analog front end of the module. With a selection of programmable filters and a set of programmable attenuators and amplifiers, the types of signals that can be acquired by the M228 are numerous.

M228 1MSPS Aperture A/D (Part 1)

2009-01-30T11:46:00.000-08:00

We are excited about our newest M-Module, the M228 1MSPS Aperture A/D. In fact, we are so excited that I'm planning not just one, but a series of articles about this module, this being part 1. This module has some unique features that position it well in the data acquisition market.

First the basics: The M228 is a 1 Mega-sample per Second (MSPS) 14-bit A/D Converter capable of sampling and storing differential analog signals (up to +/-60V) at a rate up to 1MSPS. All samples can be stored at the specified sample rate or an aperture feature allows real-time selective storage of samples based on software configuration. A 32-bit timestamp is stored along with the data to allow correlation of stored data with real time. The data and the timestamp are together referred to as a time-value pair. The M228 is capable of storing up to 32M time-value pairs in onboard RAM.

The aperture feature will be discussed in detail in part 2 of this series but it merits a brief description here. The basic behavior of the aperture feature is that an aperture window will be configured using aperture high and aperture low settings. When an A/D sample is within this window, the data is discarded. When an A/D sample exceeds this window the sampled data is stored along with its 32-bit timestamp. The aperture windows (there are actually 2 aperture windows) can be configured in many different ways providing a lot of flexibility in how the user configures the M228 to selectively store samples. For example, the aperture window can be fixed to absolute values or can be relative to the last stored value in which case the window will move along with the analog signal whenever it exceeds the current aperture window. Again, the details of the aperture feature will be discussed in part 2.

On a side note, the notion of selectively storing data is a concept that we term data extraction. At a higher level, we classify it as transient data acquisition. In data extraction, the hardware is configured to extract only the data that is of interest to the user thus reducing the amount of data that needs to be stored and reducing the amount of software and processing power needed to analyze the data. In addition, since the hardware knows which data is of interest, it can be programmed to perform other task on events that cause data storage such as generating interrupts and triggers. C&H Technologies has a number of products that fit the descriptions of data extraction and transient data acquisition. An overview of those products can be found here.

Finally, an A/D converter module is only as good as its analog front end. Like the aperture feature, this will be the topic of a future post in this series but it merits a brief description in this post. The M228 has a highly flexible, software-configurable analog front-end including the selection of a programmable Elliptic anti-aliasing filter, a programmable Bessel anti-aliasing filter or a direct (filter bypass) mode. In addition, programmable amplifier and divider circuits allow for sampling of differential analog signals of up to +/-60V. Further, calibration adjustments and a storage EEPROM for calibration values allow system level calibration to ensure precise measurements.

As you can tell, the M228 is a highly capable data acquisition module. With the flexibility of the M-Module format, it can answer many data acquisition challenges, regardless of the environment. Stay tuned for parts 2 and 3 where I will discuss more details about the unique features of this card.

2008 - Year and Review

2009-01-02T08:32:00.000-08:00

Everyone else is doing it so why shouldn't we. There is a reason everyone takes this time to review the events, accomplishments and failures of the previous year. It is therapeutic, motivational and healthy to start anew by looking at where you've been. So without further ado, here is C&H's year in review:

M215 Signal Conditioning M-Module- In January, we introduced the M215 which provides special purpose signal conditioning for low speed signals. It has two debounce channels designed to cleanup noisy switch contact closure signals and a very versatile quad window comparator function for monitoring voltage, current, or resistance.

EM405-8x106/107 Event Detector - In February, we introduced the LXI 64-channel and 128-channel Event Detectors. These products are based off of our EM405-8 LXI M-Module Bridge and our MA203 Event Detector M-Module. The product family received LXI Conformance approval in March following the the February LXI plugfest and general meeting.

VX402C-64 High Power Option - In May, we released two new versions of the VX402C-64 VME64 carrier that provide increased +5V and +3.3V power to the VME card. These new versions provide up to 34W of +5V power and up to 21W of +3.3V power. Previous versions (which are still available under an ordering option) provided 34W total for the combined +5V and +3.3V power supplies.

MA209 ( reference disciplining improvements) - In June, we introduced an upgrade to the MA209 100MHz Pulse Generator M-Module providing enhanced reference disciplining functionality. This logic allows the MA209 to discipline its internal clock to a highly stable external clock source such as a M213 GPS Timing Receiver. This functionality greatly improve the frequency stability of the MA209 pule output. See the related blog for more details.

VXI Linux Development Kit - In July, we completed and introduced a Linux Development Kit for our VXI Intelligent Carriers. This kit includes hardware, software and documentation that allows the customer to easily develop embedded applications running on our VX406C, VX407C and VX411C VXI intelligent carriers using the Linux operating system.

M227 Programmable Clock/Counter/Timer M-Module - In August, we introduced the M227. This M-Module is a highly flexible timer, counter and clock source module. It's flexibility allows for it to perform standard counter/timer tasks as well as unique time based functions. See the related blog for more details.

EM405-8 Mass Storage Option - In October, we announced a new Mass Storage Option for the EM405-8 LXI M-Module Bridge. This options provides 16 Gigabytes of non-volatile storage internal to the unit allowing a large amount of collected data to be captured and stored without overloading the Ethernet network.

M228 1MSPS Aperture A/D - In December, we introduced the M228 M-Module. The M228 is a 1MSPS A/D M-module capable of selectively storing A/D values based off a set of programmable aperture values. It contains 32 Megasamples of onboard memory and includes highly programmable front-end analog logic. Stay tuned for a future blog post discussing this module in detail.

EM405-8 Scripting Utilities - Also in late December, we introduced the addition of scripting utilities to the EM405-8 LXI M-Module Bridge. Scripting allows the user to develop on-board embedded software to control the EM405-8 and associated M-Modules. This provides vast performance improvements and allows the user to further customize his/her application. Like the M228, this upgrade will be the topic of an upcoming blog post.

A couple other notable events:

C&H staff contributed to the August Evaluation Engineering Instrumentation Test Report with an article about M-Modules. Evaluation Engineering's Instrumentation Test Report is a feature of their electronic media. The article can be read online here.

The EM405-8 was one of the featured products and C&H's Vice President and CTO, Gary Guilbeaux provided comments in the January 2009 Evaluation Engineering magazine. The article can be read online here.

M227 Programmable Clock/Counter/Timer M-Module

2008-11-16T20:57:00.000-08:00

The newest module in our quiver of M-modules is the M227 Programmable Clock/Counter/Timer M-Module. Newly released, this module is extremely flexible and, thus, provides a large number of possible timing functions. The module has three 32-bit counters capable of running up to 50MHz, two programmable front panel inputs, three programmable front panel outputs and two backplane trigger lines.

The inputs can be used to synchronize and control the three 32-bit counters. The inputs can start/stop a counter, gate a counter, clock a counter, latch a counter value, and reset a counter. The two inputs and the two backplane triggers can be routed to any of the three counters and the two front panel inputs have a programmable threshold, level sensitivity and input impedance.

The outputs can be configured to be any of the various clocks running onboard the M227, a counter carry signal, or counter match signal. It is also possible to route the outputs to an input of one or more of the counters so that the counters can be daisy chained or so that the state of one counter can control the state of another counter. The four divider networks, the clock prescaler and the three counters allow the M227 to generate clock/timing signals of just about any frequency up to 50MHz.

In addition to the high level of flexibility in the counters and the I/O, the M227 has clock disciplining logic that allows it to discipline it's internal clock to a highly accurate clock such as from an ovenized oscillator like the M207 or to the 1PPS/100PPS signal of a GPS timing module like the M213.

It is impossible to imagine all the possible functions that can be created with the M227. It's flexibility makes it a great solution to most standard counter/timer application as well as to many applications where the counter/timer function is less ordinary. Hopefully the brief description in this article helps you wrap your mind around the possibilities.

On a side note, the M227 was designed to include all the same functionality of the VX491C Counter/Timer VXI module. Two M227's on a VXI carrier can replace one VX491C, leaving room for other functionality (up to 4 more M-Modules) in the same VXI slot. Or the functionality can be moved to a different platform such as PXI and LXI.

Busy, busy, busy...

2008-08-27T20:51:00.000-07:00

I have been slacking lately when it comes to writing this blog but I promise that the engineering team at C&H has not been slacking when it comes to development. Let me try to update you as to what has been going on.

I personally have spent a significant portion of time over the last couple months completing our Linux Development Kit for C&H's VXI Intelligent Carriers. We have supported Linux for a couple years now and we have several customers that have had great success developing applications utilizing Linux on our intelligent carriers. Up to this point however, our documentation and support has been rudimentary requiring the developer to have advanced knowledge of embedded Linux development. The Linux development kit includes documentation, hardware and software that accelerate Linux development on C&H's intelligent carriers and greatly lowers the bar for developing an application.

In my last post I discussed reference disciplining. That post was a conclusion of an effort to upgrade the reference disciplining feature our MA209 100MHz Pulse Generator. The new reference disciplining features greatly improve the functionality of the MA209 and deliver greater frequency stability of pulse waveforms.

In addition to those two items, we have been hard at work completing our latest M-Module, a 3-Channel Counter/Timer module with immense flexibility that can provide both source and measurement functions. This new product will be featured soon on our website and will be a topic on this blog as soon as the product release is official. We also have in the works, an exciting update to the EM405-8 LXI M-Module Carrier and a new Data Acquisition M-Module, both to be completed by the end of the year.

Finally, in just over a week, we'll be off to Autotestcon in Salt Lake City. This gives us a chance to catch up with what the rest of the industry is doing, to collaborate with peers and colleagues from other companies and to showcase our products at one of the ATE industries' largest trade shows.

It has been a quick and busy year so far. If you follow this blog you may get the impression that not much has been going on at C&H over the last few months. In reality, the lack of activity on the blog is indicative of just the opposite. Between now and the end of the year, I should have a lot to write about as most of our recent work comes to fruition.

Reference Disciplining

2008-07-03T12:06:00.001-07:00

Time-based measurements and periodic signal sources are only as accurate as the frequency reference that is driving the measurement or signal. Oscillators used to provide the reference can vary greatly in type and frequency precision. In addition to the physical type of the oscillator, environmental conditions, such as temperature, can effect both long term and short term frequency stability.

Reference disciplining is a technique of using a highly stable frequency standard to adjust the frequency of the internal oscillator of an instrument to near (typically within one decade) that of the external reference. Using reference disciplining, the long term stability and accuracy of the internal oscillator and thus the accuracy of the measurement or signal source can be greatly improved.

For example, C&H’s MA209 100MHz Pulse Generator has a typical frequency stability specification of 50 parts per million (ppm). However, with external reference disciplining, the frequency stability can be improved to 0.01ppm.

With the MA209, an external 1 Pulse Per Second (PPS), 100PPS, or 10MHz signal can be used to discipline the internal clock. The 1PPS or 100PPS can come from a GPS timing receiver such as C&H’s M213. The 10MHz can come from an ovenized oscillator such as the M207, from a Rubidium frequency standard or from one of many other precision 10MHz frequency sources on the market. The MA209 requires an initial 10 minute module warm-up period, after which the internal clock will discipline, in typically 30 seconds, to within one decade of the external reference, up to the specified stability.

It is important to distinguish reference disciplining from the more complex technique of phase locking which is typically performed with a phase lock loop (PLL). The same results can certainly be achieved with a PLL and a PLL can provided further benefits; however, we typically do not desire the added complexity nor need the added benefits. In contrast, reference disciplining is a straightforward solution that uses the short term stability of a common voltage controlled oscillator and the long term stability of an external reference to create highly stable frequency source.

Reference disciplining is incorporated into a number of C&H’s M-Module instruments including the MA204, MA208, MA209 and the forthcoming M227. In any instrument where the stability of the frequency source is important, reference disciplining is key to achieving the most accurate and precise measurements.

Feel the Power

2008-05-02T13:54:00.000-07:00

I'm feeling very powerful these days. It has to be the PowerPC, the ARM processor, Embedded Linux, M-Modules, ANSI-C drivers, APIS, PXI Modules, PMC Modules, the VX406C, the VX407C, the VX411C, and the EM405-8 or, in other words, C&H's Intelligent Carriers. The marriage of an embedded processor with the power of open source Linux and the countless number of instruments in the M-module, PMC and PXI formats creates a very powerful product line with limitless possibilities.

I recently wrote a simple demo application for a customer utilizing the VX406C running Embedded Linux and the M395 16-Channel DAC M-Module. This embedded application creates 4 custom VXI Word Serial Commands: “volt” – sets the DAC output, “volt?” – queries the DAC output, “sweep” – sweeps the voltage from 0 to 5 volts, and “clearirq” – clears a pending interrupt. The commands “volt” and “volt?” are self explanatory. The command “sweep” starts a sweep of the DAC output from 0 to 5 volts in 1-bit increments dwelling for 1ms at each point. When the sweep completes, the application generates a VXI interrupt. The command “clearirq” clears the generated VXI interrupt. The host software consists of a small GUI allowing the user to interactively send the commands. When the “sweep” command is sent, the host software starts a counter and continuously updates the counter illustrating that the sweep, indeed, runs asynchronously on the PowerPC residing on the VX406C. When VX406C completes the sweep and generates the VXI interrupt, the host software receives the interrupt and handles it appropriately stopping the counter and going back to normal.

Yes this is a very simple example, but it illustrates the power of the intelligent carriers and opens the mind to the possibilities available with this architecture. Even more important is that the application, utilizing the M395 ANSI-C driver, the VX406C Linux APIS Platform Support Module, and the standard Linux toolset, took less than half an hour to write (the source code can be viewed here). It goes to show that it is extremely simple to create a basic application that can be expanded upon to add features and functionality.

A more complex example is an antenna tuner utilizing the VX407C, a PXI Arbitrary Waveform Generator (ARB) and a PXI digitizer. In this application, the ARB output and the digitizer inputs were connected to a separate device that performed attenuation, amplification and coupling to/from the antenna. The digitizer received a reference signal from the ARB and a reflected signal from the antenna. As in the above example, a sweep command was created. When the sweep command was received, the embedded application would step the ARB through a range of frequencies. At each frequency, the embedded application would digitize both the reference and reflected waveforms, would perform an FFT on each digitized waveform and would use the FFT results to calculate a Voltage Standing Wave Ratio (VSWR). The host software would only retrieve an array of VSWR measurements. Imagine the VXI or PXI traffic and the processing power required to perform this in a standard setup. By dedicating an embedded processor to this task the host is free to manage its other responsibilities.

The above examples are just a taste of what can be created with C&H's intelligent carrier architecture. With well over 100 different M-modules and countless PMC and PXI modules, you can just envision the possibilities. With the addition of Linux and the vast array of open source tools that come along with it, this platform becomes very, very powerful.

m395_demo.c

GPS - Do you know where your test system is?

2008-04-02T19:59:00.000-07:00

OK, I agree...that title is a little misleading. While GPS is popularly known to provide accurate position data anywhere on the globe, it's use in test systems is far different. A lesser known feature (lesser known outside of the scientific and engineering world) of GPS is the precise time reference that can be used to, among other things, synchronize clocks or discipline frequency sources to provide long-term clock stability. It is this feature that is of interest in the world of test and measurement.

The M213 M-Module is a GPS Timing Receiver capable of producing a highly accurate 1 Pulse Per Second (PPS) or 100 Pulse Per Second signal.

The M213 utilizes the M12+ Timing Receiver formerly manufactured by Motorola now manufactured by iLotus, LTD. and distributed by Synergy Systems. The M12+ is specifically designed for timing applications. The M12+ can track up to 12 satellites simultaneously and includes an algorithm known as Time-Receiver Autonomous Integrity Monitoring (TRAIM) that ensures the integrity of the PPS signal. The M213 actively monitors the PPS signal providing status of the signal via a front panel LED and a software register. In addition, the M213 can generate an interrupt on any change of status of the PPS signal. The M213 can be programmed to output a 1 PPS or a 100 PPS signal and the PPS can be configured to be active all the time, never, only when tracking at least one satellite or only when the TRAIM conditions are met.

A software driver is available that allows easy integration into any test system and like all of C&H's drivers, it includes a soft front panel application that provides out-of-the-box interactive control of the module. Finally, being an M-Module, the M213 can be used in any platform for which there exists an M-module carrier, including, VXI, VME, PXI, cPCI, LXI, and more.

While you certainly could monitor the location of you test system using the M213, it is not likely to be of interest. On the other hand, the ability to discipline a frequency source to provide extreme long term stability can be invaluable for many applications.

Event Detectors Receive the Official LXI Stamp of Approval

2008-03-12T21:19:00.001-07:00

A quick follow-up to the post titled Reflections of the LXI Plugfest and General Meeting:

At the LXI Board of Director's Meeting on March 10th, our application for class C conformance for both of our Event Detector Products (EM405-8x106 and EM405-8x107) was approved. The products have been added to the LXI Consortium's official list of conformant devices.

LabView Support for M-Module Instrument Drivers

2008-03-02T21:32:00.000-08:00

I few weeks ago, I recieived a call from a customer wanting to use our MA204 VXIpnp Driver in LabView. While we have experience using LabView to call VXIpnp drivers, we had not, as of this phone call, attempted to use LabView with a driver written in our new APIS base architecture. The Ma204 driver was migrated to this architecture late last summer and I must admit, when I received this phone call I had to cross my fingers.

The bottom line result from this call was that it worked as adveritsed. The customer was able to use LabView to control the Ma204 Pulse Generator and went forward with their LabView application development. The process is actually very simple.

LabView has had, for a long time, a utility to convert LabWindows/CVI device drivers into LabView libraries complete with VI's for each function in the driver. In LabView versions prior to 8.0, this utility was available from any VI using the menu item Tools>>Instrumentation>>Import CVI Instrument Driver. In LabView 8.0, the menu name was changed to Tools>>Instrumentation>>Create VI Interface to CVI Instrument Driver. Beyond LabView 8.0, this utility was removed from the normal LabView installation and instead, is available as an independent download referred to as LabView Interface Generator for LabWindows/CVI Instrument Drivers. This tool is available as a free download from ww.ni.com.

Running this tool is a matter of iterating through a simple wizard. The tool uses the CVI driver's function panel (.fp) file to create LabView VI's for each function in the library. The VI's are implemented using LabView's Call Library Function Node which is LabView speak for a utility that allows LabView to call a standard Windows Dynamic Link Library (DLL). In this case, the DLL being used is the CVI driver's DLL.

All of our M-module drivers include a Windows DLL and a CVI function panel (.fp) file. Therefore, all of our M-module drivers can be used in LabView. As the case from a few weeks ago proves, the process is simple and dependable. If you would like to use one of our driver's in LabView and would like further details or assistance with this process, please contact us and we will be happy to support your efforts.

Reflections of the LXI PlugFest and General Meeting

2008-02-25T08:44:00.000-08:00

I attended the LXI Consortium's PlugFest and General Meeting in Newport Beach, CA on February 11-13. The LXI Consortium holds these meetings once a quarter at sites throughout the world. This was by far the heaviest attended meeting to date. C&H has attended at least half a dozen of these meetings since 2006 and we've noticed the continual growth in participation. This bodes well for LXI and all those involved. I am continually amazed at how well a group of competitors can collaborate for the betterment of the industry and I'm not strictly speaking about the collaboration on writing the specifications. Short of providing proprietary source code or design details, you find at these meetings, engineers providing guidance, advice and even debug assistance that help better a competitors instrument(s). The type of help that is unheard of in other industries.

There were several components of the 3-day meeting some of which happened in parallel. On the first day, C&H participated in the Class C Multivendor System Demo (MVSD). This involved connecting several different vendors' instruments, including our EM405-8, to a network, and performing same basic connectivity tests. We tested LXI discovery and Identification on all the major software vendor's tools (Agilent, Mathworks and National Instrument). We pulled up web pages and XML files. We performed tests such as removing the DHCP server and verifying that all the instruments switch to an AutoIP configuration. The good news about this testing, was that there was no news. It may be uninteresting, but it is great that there were no major problems with any of instruments nor any of the software vendor's products. According to Rob Purser of Mathworks who has been in charge of the MVSD work for the last couple years, this is the first time things have gone so smoothly. This tells me that the products are starting to mature to a point where the Class C features have a solid foundation.

In parallel with the Class C demo, a group of engineers performed some Class B (IEEE-1588) testing. As expected, there were more difficulties than the Class C testing but they were able to create a system of class B devices and get the clocks synchronized with a precision on the order of nanoseconds. I was not involved with this testing so I don't know details but the reports were very promising.

A large part of the meeting was dedicated to "lowering the barrier" to 1588. This included the demo/testing discussed above, open discussions amongst the attendees, and presentations by 1588 tool vendors. The common themes of all this discussion and presentations were that 1588 works, 1588 is useful and desirable, 1588 will become an increasingly import feature of LXI instruments and 1588 is becoming easier to implement by instrument vendors.

The second day was full of presentations discussing all of the current happenings with the LXI consortium. The LXI Standard Version 2.0 is currently in works and there are many technologies being worked on and several more being explored. Some of these include, improved web support for triggering, resource management, scripting, and IEEE 1588-2008. The consortium is very active and is building upon a solid foundation by adding features that improve the user's experience with LXI instruments. C&H is closely following these improvements and we will continue to adapt our LXI offering as the specification improves.

The final day was open to the public and consisted of presentations by LXI members and users. In addition, the final day was reserved for compliance testing and we brought our LXI Event Detector along to be tested. Compliance testing involves sitting down with Lynn Wheelwright, the consortium's compliance guru, and running through a sequence of tests that verify that your device meets the LXI specification. Every rule of the specification is verified and your instrument is poked and prodded to make sure it is compliant. The entire test is guided by a piece of software written by Lynn called the LXI Compliance Test Suite. Several of the tests are automated; however, most of them require some sort of user intervention or simple manual verification.

The test process did expose a few LXI rules in which our device was non-compliant; however, every one of them was fixed on the spot and we were able to leave the meeting requiring only paper work and the release and registration of the IVI driver in order for us to achieve certification. What was most interesting about our testing was that it exposed a couple items that existed in the EM405-8 which received compliance in 2006. That is a testament to how far the testing has come. The problems were nothing that affected the functionality of the carrier but they were problems non-the-less and we were grateful that the test exposed them. More robust testing like this no doubt improves the quality of our products.

The meeting was a success. We left with everything needed to achieve compliance and we learned a lot about the future additions to the LXI specification. Our compliance paper work has since been submitted and the IVI driver has been registered on the IVI Foundation website. We are a compliance committee review and a board of directors meeting away from formal approval of our second LXI device. We are excited about LXI and its growing demand in the marketplace. It seems that so is the rest of the Test and Measurement Industry.

Event Detectors

2008-02-07T20:29:00.000-08:00

My efforts over the last couple of weeks have been focused on preparing our 64/128 Channel Event Detector products for LXI compliance testing. While the compliance testing effort is interesting enough, it is actually the features of the Event Detector itself that I would like to focus on. We can discuss LXI compliance testing in a couple of weeks after I return from the LXI plugfest in Irvine, California.

The Event Detector is by no means a new product. We have been shipping the MA203 Event Detector M-module in both VXI and PXI systems since 1999. In fact, to date the MA203 install-base resides at over 430 units. This new offering of Ethernet Event Detectors consists of the same MA203 M-Modules integrated into an EM405-8 carrier in either a 64 or 128 channel configuration.

The Event Detector works by sampling all channels in parallel and selectively storing the samples along with a 31-bit timestamp into a FIFO. At every period of the programmable sample clock, the event detector samples all channels in parallel. It then compares the sample with the previous stored value and determines if any of the watched inputs have toggled. If an input has changed, the entire sample is stored along with the timestamp. The process repeats at a rate of up to 5MHz. The Event Detector features a highly programmable sample clock and the capability to use an external clock of up to 5MHz. It also includes per-channel programmable input thresholds of up to 25 volts, programmable debounce logic, and extensive triggering utilities for synchronization.

The key feature of the Event Detector is the ability to store samples only when one or more of the watched inputs have change. This provides real-time data compression and takes the burden off software to recognize and determine the interesting part of an acquisition. We call this “Data Abstraction.”

At Autotestcon in September, we demonstrated the 128 Channel Event Detector with a game that required users to press a sequence of buttons to cause events. When a user started the game, the Event Detector began continuously sampling all 128 channels at 5MHz. Events occured when a user pressed one of the toggle buttons during the game. Each play of the game typically lasted about 3 seconds. We kept statistics during the show and after three days, we had sampled a total of 14 minutes and 59.91 seconds. In that time, we received a total of 791 events and transferred across the network a total of 10.04 kilobytes (including timestamps). In stark contrast, if we would have used a standard Data Acquisition module that stores every sample at 5MHz, we would have transferred 25.14 gigabytes. In addition, a large amount of processing power would have been required to monitor the data to find the events. This example is a clear illustration of the advantages of the Event Detector and its ability to perform data abstraction. The contrast of the amount of data as compared to a continuously sampling data acquisition module is remarkable.

In just over a week we will obtain LXI compliance on the 64 and 128 Event Detectors. Beyond that, we plan to continue advancing this technology and adding products that compliment this functionality as well as our entire product line.

Introduction - Who is C&H?

2008-01-18T14:32:00.000-08:00

For my first post, I considered skipping the typical introduction and going straight to the meat and potatoes of this blog – news and commentary on all things C&H including the industry in which we live, the products we create and the employment of those products in various applications – but, I’ve reconsidered. A little self reflection is always valuable and there are those of you, unfamiliar with C&H, who upon finding this blog will head straight to this first post to find out what this is all about.

Who are we? What do we do? In short, C&H designs and manufactures instrumentation and other electronics for the test and measurement industry. In fact, we have nearly 100 different products spanning a wide spectrum of functionality including sources, measurement, data acquisition, switching, digital and analog I/O, and serial communications.

So what is different about us? Our approach is unique and is best described not in words, but in a picture and a single tag line "Platform Independent Instruments."

We focus on instruments in the ANSI standard M-module format and we provide the tools to use those instruments in any platform. In addition to the M-modules themselves, we provide M-module carriers for all of the major platforms used in the test and measurement world. This opens up a world of functionality to the test and measurement industry making available a large number of devices, not only from C&H but also from almost a dozen other M-module manufacturers. A comprehensive list of available M-modules can be found here.

In addition to M-modules and M-module Carriers, we manufacture several other unique products for the test and measurement industry. Products such as: the VX407C Intelligent PXI Carrier for VXI, the VX411C Intelligent PMC/PCMCIA Carrier for VXI, the VX402C-64 VME, VXI (As or B size) or VME64.carrier for VXI, Industry Pack modules and carriers for both VXI and PXI, and a collection of Standard VXI instruments.

More details on all of these products and on C&H in general can be found on our website. For direct inquiries you can contact us at support@chtech.com or sales@chtech.com. In addition, your local sales rep will be happy to answer any of your inquiries.