Increase Productivity & Decrease Test Costs by Using the Same Instruments During All Test Stages
Modular or Bench-top?
Historically, there has been a clear division between bench-top and modular test and measurement instruments. This division is demonstrated when comparing bench-top and modular instrumentation use cases. Bench-top or rack and stack instruments are typically used for manual and interactive tasks, such as design engineering or troubleshooting. In contrast modular instruments, or instruments on a card, are typically used for automated tasks, such as manufacturing and service test. Due to the uniqueness of each use case, instrument suppliers have provided vastly different products to address each need. The product features, peripherals, and deliverables (user manuals, software drivers, etc.) address only one of the two use cases. The result is two types of instruments with little overlap between users or suppliers.
As product development and production cycles shorten, instrument users are blurring the lines between manual and automated use cases. Engineers are now comfortable with software tools and inclined to automate their job activities, such as design validation. Production test engineers, pressured to meet tight delivery schedules, will often reuse both hardware and software used by the product development team.
Fortunately, with the advance of PC-based software tools and techniques, the division between modular and bench-top instruments has become less distinct. Modular instruments are providing more bench-toplike functionality and bench-top instruments are providing more modular-like interconnectivity. As a result, a trend is taking place towards the convergence of modular and bench-top test and measurement.
It is possible, and often preferable, to solve different test and measurement use requirements with common “enterprise” instrument hardware. An enterprise instrument provides the requisite hardware versatility and software elements that can be easily adapted to extremely different use requirements. The following discussion defines those use cases, the hardware and software features, and gives an example of an enterprise oscilloscope solution.
Historical Modular Use Cases
Modular instruments are used predominantly as test assets within automated test equipment (ATE) applications. ATE applications leverage the strengths of modular instruments such as lower prices, easier system integration, and smaller footprints. Most ATE applications consist of pre-defined and programmed functional tests requiring little manual interaction other than supervisory control.
By virtue of the targeted ATE use case, most modular instrument vendors provide comprehensive software drivers supporting many software development platforms to enable end users to easily integrate and automate the hardware products. High-quality software drivers are a key element for modular instrument integration success. Also, modular instrument vendors have developed graphical user interfaces, signal analysis software, and extensive PC based tools to empower customers to develop custom software solutions.
Many of the aspects of modular instruments that make them well-suited to ATE limit those same modular instruments from being easily adapted for manual users. For example, when packaged within an ATE system, modular hardware may be limited by the physical constraints of the hardware platform, fixed high-density cable harnesses, or lack of local interactive controls and displays. Outside of ATE, modular instruments require a cumbersome and costly configuration of system hardware (typically including a chassis and controller) and software. Most manual users require a portable solution that can be easily setup for immediate testing and diagnostics of a device under test (DUT).
Historical Bench-top Use Cases
Bench-top instruments are used predominantly in a manual fashion by design and test professionals trying to validate or diagnose a DUT. This manual use requires a physical footprint that can be easily moved to the DUT. The hardware user interface must provide the appropriate physical controls (such as knobs, switches, and buttons) and display elements, and must be designed for a manual user to enable its rapid setup and intuitive use.
As noted earlier, the bench-top instrument user often works in a development or troubleshooting role, and requires the hardware to provide a complete and flexible solution. All functionality must be easily and instantaneously available without requiring software installation or development. Also, where modular instrument users can add software-based features and functionality, the manual user is often limited to only what is available within the hardware instrument. Consequently, bench-top hardware typically provides more comprehensive test and measurement functionality to cover many applications.
Bench-top instruments often present shortcomings when a user tries to automate tests or integrate the hardware with software or other instruments. The hard displays are bulky and cannot be adjusted for different users or applications. The internal algorithms and operations are less flexible and often difficult to access for quick diagnosis. Bench-top instrument vendors often do not offer the wide-ranging integration and automation software tools and support that are the necessary peripherals commonly provided with modular products.
Merging Use Cases
Merging the diverse use cases of modular and bench-top instruments is possible. Modular instruments can supplant the equivalent bench-top products when offered with the proper hardware and software feature sets. Such relevant features include: (1) turn-key software front panels (SFP) that emulate the expected physical controls and displays1, (2) universal software to enable access and interoperability without unique or licensed software, (3) comprehensive hardware functionality that reduces or eliminates software development2,3,4, (4) high-throughput data connectivity to enable real-time display, and (5) instrument portability.
Enterprise Instrumentation
Synthetic vs. Enterprise
Synthetic instrumentation is implemented on generic hardware, where the underlying hardware is not explicitly designed to perform a particular function. The underlying synthetic hardware is designed to be general purpose, and application-specific functionality is provided in software.
Whereas synthetic instruments may be configured to address a variety of applications, enterprise instruments may be configured to address a specific application for different users throughout an organization. Enterprise instrumentation is comprised of application-specific instruments that can be configured through software to expose different levels of complexity or functionality to address different use cases. The underlying enterprise hardware must provide comprehensive application-specific functionality to serve the complete set of test and measurement needs throughout research and development, design verification, production test, and service and repair of a specific product or application.
Versatile Hardware
Instrument versatility is a key element that is necessary to allow a modular hardware product to be applied throughout an organization as an enterprise instrument. In the above section Merging Use Cases, items 3-5 list the hardware elements that provide this versatility: comprehensive functionality, high data throughput, and instrument portability
For an intended application, comprehensive test and measurement functionality must reside within hardware. Complex application-specific software development should be dramatically reduced or eliminated. End users should only need to implement software to address their business use cases for instrument automation, data presentation, and data archival, and NOT be required to develop compliance test and measurement expertise and algorithms. A hardware product that requires low-level programming to implement basic test and measurement functionality will not often be used in a manual fashion.
High-throughput data connectivity is essential when interacting with a modular instrument using a software front panel (SFP). Manual or remote interaction using a SPF requires real-time display update rates to emulate the expected performance of the bench-top instruments that they are replacing. High-throughput LAN or USB connectivity may provide such data rates, but this essential hardware characteristic must not be overlooked.
Manual instrument use demands physical aspects that enable instrument portability. For example, a modular instrument must be able to be transported close to the DUT without requiring its installation within a PC, or the movement of an entire PC. This aspect is often overlooked, but bench-top instruments are often preferred because of this instant-on feature. In order to supplant bench-top instruments in manual-use cases, modular instruments must also provide instant-on capability. Some modular platforms such as LXI do address this requirement.
Essential Software
Software provides the enabling functionality to adapt and expose the necessary features for the variety of use cases. Software is by definition highly flexible. Unfortunately, most technical professionals do not have the time or resources to program or configure all necessary software for the various use scenarios across an organization. Consequently, the burden falls upon hardware vendors to provide the essential software tools to empower the end users in all areas of the enterprise. In the above section Merging Use Cases, items 1-2 list the essential software elements that enable this capability: turn-key software front panels (SFP) and universal software.
Turn-key software front panels (SFP) that emulate the expected physical controls and displays of the supplanted bench-top instrument are essential in establishing their use in the manual steps of development and troubleshooting. Emphasis should be placed upon the quality and intuitiveness of the SFP that is delivered with the modular instrument.
SFP applications should be developed using open or universal frameworks that enable access and interoperability without unique or licensed software. The manual-use application software should be deployable across the corporate environment without requiring complicated installation procedures or expensive licensing requirements. Also, software tools enabling interoperability with third-party software tools are necessary for specific use cases such as: a test executive for automated test, spreadsheet or database software for functional validation, or computation software for design & development analysis or modeling.
Enterprise Benefits
By selecting the appropriate modular instrument hardware and software, an entire corporation may apply the same modular instrument throughout the entire enterprise. This has substantial benefits by providing for a consistency of algorithms, redundancy of equipment for calibration and backup, cross-training and cross-support capabilities, and quantity discounts from instrument vendors.
Enterprise Oscilloscope Example
An oscilloscope is a ubiquitous test and measurement tool that is used throughout product’s development and deployment lifecycle. Often times, different oscilloscope hardware is selected to address different user needs across a corporation. The following example demonstrates the application of a singular modular oscilloscope configured to support four different use-cases across an enterprise.
Figure 1. Manual-Use LXI Tablet Oscilloscope
For this example, an enterprise oscilloscope platform is provided by a ZTEC ZT4611 LXI modular oscilloscope shown in figure 1. Local manual display is provided on a tablet PC using the ZTEC patent-pending Tablet Oscilloscope Protocol. Remote or automated use is accomplished using third-party software tools integrated with ZTEC-supplied software drivers, services and SFP widgets.
Research and Development Use Case
Research and development engineers typically use the most extensive and powerful features of the modern digital storage oscilloscope. Often, those manual acquisition and measurement needs are unique and non-repetitive. A full-featured oscilloscope SFP, such as ZScope™ shown in figure 2, is required to provide the full instrument capabilities to this expert user. The interaction provided by the SFP on the local display emulates the experience of a typical bench-top oscilloscope.
Figure 2. Full Feature Oscilloscope Software
Design Verification Use Case
Design verification techniques using an oscilloscope typically require semi-automated user interaction. The engineering professional may perform a variety of tasks ranging from basic manual to sophisticated automation such as limit or mask testing to determine product compliance. The design-verification SFP should provide data logging services, such as those shown in figure 3, to record and report validation data using standard third-party software tools such as spreadsheets or structured query language (SQL) databases.
Figure 3. Design Verification Software
Production Test Use Case
Production test or ATE is the most common use case for modular instrumentation. Within an ATE system, the modular oscilloscope is mounted with other test equipment to perform sequences of automated functional tests using test executive software such as that shown in figure 4. ATE hardware must be easily rack mounted. Many instruments are integrated into a single test system, so all the hardware and software must comply with the appropriate industry standards. High quality software drivers and third-party interoperability services are required to ease the ATE system integration and development. Interoperability services include interfaces to standard third-party software tools for test data archival, statistical process control (SPC), quality control, and other business operations.
Figure 4. Production Test Executive Software
Service and Repair Use Case
Service and repair technicians often require a reduced-feature oscilloscope SPF that provides for simplified acquisition and measurement techniques. Figure 5 shows a typical reduced-feature oscilloscope for service and repair use. These operations are typically performed in a manual fashion, but may involve more automation and data reduction. Also, interaction with a knowledgebase for common troubleshooting and repair techniques is a common requirement.
Figure 5. Service-Specific Oscilloscope Software
Other Enterprise Use Cases
Mixed Use and Re-Use
In each use case example, the pertinent subset of enterprise instrument functionality is provided to the end user as needed. The desired functionality is primarily defined by the software interface. Because software is the key element for each use case, the enterprise instrument can be adapted to support a mixed use case environment as well. For example, a design engineer can easily access the full-featured SFP on the production floor to assist with troubleshooting. Validation engineers can easily share code and algorithms with both engineering and production. The enterprise instrument facilitates an integrated approach to product development and production through software transportability and re-use.
Multi-Platform Use Case
Another reality facing the enterprise instrument user is the need to support multiple hardware and software platforms. Individual departments within an organization have unique needs and may not be able to adopt a single enterprise solution. For example, many production test departments have already made the decision to standardize on PXI or VXI hardware. In addition, different users within the organization may have different operating system and programming environment software preferences.
To accommodate multi-platform needs, a neutral approach to hardware and software is needed. This approach allows users to transport identical instrument functionality to many different hardware and software platforms. In essence, the hardware and software platforms should become transparent to the end user, providing fewer constraints on platform choices.
Figure 6 shows enterprise instrumentation hardware that supports multiple bus architectures. The hardware and software functionality of the depicted ZTEC oscilloscopes is identical for all of the different physical architectures.
Figure 6. Multiple Hardware Platforms
Transparent software support is another key component of a platform neutral approach. As shown in figure 7, companies like ZTEC provide software options that allow code and application transportability among commonly used hardware and software platforms.
Figure 7. Multi-Platform Software
Summary
The enterprise instrumentation concepts presented in this paper describe a means for leveraging modular instrumentation across a broad set of use cases throughout an entire corporation. When provided with the proper modular instrument hardware and software features and tools, end users may utilize modular instruments in ways not previously considered. The use of common enterprise instrumentation provides substantial benefits in the consistency of test and measurement algorithms, redundancy of equipment for calibration and backup, cross-training and cross-support capabilities, and quantity discounts from instrument vendors.
References
[1] User Interface System and Method, Patent Pending, USPTO Registration Number 42,599.
[2] J.A. Mielke, Improving Performance in a VXI or PXI Test System Using Distributed DSP, 2004, IEEE AUTOTESTCON Proceedings.
[3] C.D. Ziomek, et al., The Need for Embedded Intelligence in ATE, 2005, IEEE AUTOTESTCON Proceedings.
[4] C.D. Kuenzi, et al., Fundamentals of Oscilloscope Measurements in ATE, 2006, IEEE AUTOTESTCON Proceedings.