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`kkREE RAKE CAR-RT SORT ** COO3
`576 517 O15
`38
`APRS
`UNIV. OF WISCONSIN
`K F WENDT LIBRARY
`215 N RANDALL AVE
`MADISON. WI
`53706-1605
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`nl
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`COLLEGE OF ENGINEERING
`
`MAY 28 1998
`
` KURT F. WENDTLIBRARY |
`
`UW-MADISON, WI 53706
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`sound and vibration
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`®
`
`THE NOISE AND VIBRATION CONTROL MAGAZINE
`Noise and Vibration Control e Equipment Reliability
`Structural Analysis e Dynamic Measurements
`Dynamic Testing
`VOLUME 32/NUMBER 4
`APRIL 1998
`
`EDITORIAL
`
`Some Things Change and SomeThings Remain the Same! ............5
`Patrick L. Walter
`
`FEATURES
`New Developments in Large-Scale
`Dynamic Data Acquisition SySteMs.......sesceseeteneseeeeneeeesusseerveeasa 18
`Strether Smith, Steve Katz, Bill Hollowell, Eric Olson, Al Brower,
`Bob Franz and Scott Snyder
`
`A Mixed-Mode Smart Transducer
`Interface for Sensors and ACtuatOFs........cccccccececceceeeeeeeeseeneeeeeeeeeenees 24
`Steven C. Chen and Kang Lee
`
`Dynamic MeasurementInstrumentation Buyer’s Guide.......... seeneeee 29
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`S&V Observer ...........
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`
`COVER
`The cover photograph depicts |Otech’s new WaveBook/516 portable PC-based data ac-
`quisition system being used in “Hummer”vehicle testing atAM General Corporation’s test-
`ing facility in Livonia, MI. The WaveBook /516 provides 1-MHz speed data acquisition while
`maintaining 16-bit resolution. This performance accommodates multichanneldata collec-
`tion for test and measurementapplications such as: vehicle noise and vibration testing which
`require high resolution. (Photo courtesy of |Otech, Cleveland, OH.)
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`7 4B SWEET es ETE ewe BW EEL EGA G&G BE CUE IEWUMUMaovwi
`
`Interface for Sensors and Actuators
`
`Steven C. Chen, Aeptec Microsystems, Inc., Rockville, Maryland
`Kang Lee, NationalInstitute of Standards and Technology, Gaithersburg, Maryland
`
`
`
`This article discusses someof the key issues of the proposed
`IEEE P1451.4 standard — the existing mixed-mode transducer
`communication schemes, the Transducer Electronic Data
`Sheet (TEDS) requirements, compatibility with legacy systems,
`and utilization of results of other P1451 developmentstole-
`verage existing and emerging sensor-networking technologies.
`
`1451.2
`
`Smart
`Transducer
`Interface
`Module
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Network
`Capable
`Application
`Processor
`P1451.3
`(NCAP)
`Channel
`\
`kK >}__Interface=o ~
`Today, the transducer industry produces and utilizes mainly
`ero ce sree
`Module
`analog transducers, Interfacing these transducers to measure-
`ment and control systems is a major and costly undertaking.
`|
`| pidsit
`|
`\ Common
`While digital communication is the trend of the future, the
`P1451.4
`|
`|
`Object
`heal
`issue of interfacing analog transducers with additional smart
`heuer | a Mixed-Mode
`features to legacy systems should be addressed.
`Transducer
`The test and measurement community requires transducers
`with built-in identification which also fulfill more common
`requirements: 2 wire system, small size, low cost, low power
`consumption, etc. The test and measurement community will
`be best served with a standardized transducerinterface and a
`uniquely identifiable set of standardized protocols.
`Dueto the lack of such a standard, some transducer manu-
`facturers have introduced varioussolutions but have seen lim-
`ited acceptance. An independentand openly defined standard
`will reduce risk for potential users, transducer and system
`manufacturers, and system integrators. This will accelerate the
`XDCR
`Interface
`Ms
`High Level
`emergence and acceptance of this technology. Therefore, the
`
`coceeces P1451 Logic
`
`Object
`project, IEEE P1451.4, was established to develop a standard
`that allows analog transducers to communicate digital infor-
`mation (mixed-modeoperation) for the purposes of self-iden-
`tification and configuration.
`The IEEE P1451 Working Groups have been working on-a
`uniform approach for connecting sensors and actuators to com-
`munication networks, control systems and measurementsys-
`tems. The P1451.1, 1451.2 and P1451.3 efforts focused on net-
`work-capable sensors and actuators with digital readings. The
`P1451.4 effort proposes a mixed-mode smart transducer com-
`munication protocol based on existing analog connections.
`It also specifies TEDS formatsfor interfacing analog transduc-
`ers with additional smart features to the legacy systems. The
`proposed interface will be designed to be compatible with other
`P1451 network-capable transducerinterfaces.
`
`
`
`
`
`
`
`Network
`
`Figure 1. IEEE P1451 family relationship.
`
`|
`
`P1451.4 Mixed-Mode
`Interface (MMI)
`
`
`
`Transducer
`TEDS
`
`IEEE P1451.4
`Mixed-Mode
`Transducer
`Network
`
`
`
`
`Figure 2. IEEE P1451.4 interface.
`
`definition of the P1451 family specification. The IEEE P1451.4
`interface is needed both to allow the use of existing analog
`transducer wiring and also for those demanding applications
`whereit is not practical to physically include the Network
`Capable Application Processor (NCAP) with the transducer. Ex-
`amples of the latter include very small transducers and very
`harsh operating environments.
`Each P1451.4-compliant mixed-modetransducer would con-
`sist of at least one transducerand the interface logic required
`to control and transfer data across various existing analog in-
`terfaces (see Figure 2). The transducer TEDSwill be minimized
`and defined such that it contains enough informationto allow
`a higher level P1451 objectto fill any gaps in its TEDS.
`Scope. This P1451.4 Working Group will propose a standard
`that allows analog transducers to communicate digital infor-
`mation with an IEEE P1451 object. The standard will define the
`protocol and interface. It will also define the format of the
`transducer TEDS. The transducer TEDSwill be based on the
`IEEE 1451.2 TEDS, The standard will not specify the transducer
`design, signal conditioning or the specific use of the TEDS.
`Purpose. A standard is needed that allows analog transduc-
`ers to communicate digital information for the purposes ofself-
`identification and configuration. Dueto the lack of a standard,
`some transducer manufacturers have introduced varioussolu-
`
`tions but have seen limited acceptance. An independent and
`
`SOUND AND VIBRATION/APRIL 1998
`
`
`P1451.4 Proposed Standard
`The proposed standard will define an interface for mixed-
`modetransducers(i.c., analog transducers with digital output
`for control andself-describing purposes) as part of the P1451
`family of standards(see Figure 1). It will establish a standard
`that allows analog-output, mixed-modetransducers to commu-
`nicate digital information with an IEEE P1451 compliant ob-
`ject. Both sensors and actuators are supported andthe exist-
`ence of the P1451.4 interface is invisible from the network
`viewpoint.
`It is the intentthatall of the standards in the IEEE 1451 fam-
`ily can be used either as stand-alone or with each other. For
`example, a ‘black box’ transducer with a P1451.1 object model
`combined with a P1451.4-compliant transducer is within the
`
`ICP is a registered trademark of PCB Piezotronics, Inc.
`MicroLANis a registered trademark of Dallas Semiconductor, Inc.
`LabVIEWis a registered trademark of National Instruments, Inc.
`IBASIC is a registered trademark of Hewlett-Packard Company
`DeltaTronis a registered trademark of Briiel & Kj@r
`
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`

`
`
`
`
`P1451
`
`
`Mixed-Mode
`
`
`
`
`Transducer
` a
`
`
`
`
`
`Conversion
`
`|" P1451.4
`
`
`
`
`
`Network
`
`
`Data
`Acquisition
`
`Multiplexer
`
`High Level
`P1451
`TEDS
`
`TEDS
`Extraction and
`
`Mixed-Mode
`Inteface
`(MMI)
`
`
`Figure 3. IEEE P1451.4 compatible NCAP.
`
`openly defined standard will reduce risk for potential users,
`transducer and system manufacturers and system integrators.
`This will accelerate the emergence and acceptanceof this tech-
`“nology.
`TEDS. The P1451.4 TEDS shall be compatible with the
`1451.2 TEDS with the goal to minimize thesize of nonvolatile
`memory. The key consideration for TEDS designare: relevant
`information that help the user, “plug-and-play” functionality,
`supportforall transducers, opennessfor individual needs and
`compatibility to 1451.2. The P1451.4 TEDS shall include the
`following categories:
`1.Identification Parameters
`a. Manufacturer name
`b. Model number
`c. Series number
`d. Revision number
`e. Date code
`2,Device Parameters
`a. Sensor type
`b. Sensitivity
`c. Bandwidth
`d. Units
`3.Calibration Parameters
`a. Last calibration date
`b. Correction engine coefficients
`4.Application Parameter
`a. Channel identification
`b. Channel grouping
`c. Sensor location and orientation
`The most recent proposed TEDSincludes a 256-bit, non-hu-
`man-readable compact-TEDS and additional human-readable
`TEDS. The compact-TEDS enables the minimum implementa-
`tion of a P1451.4 TEDS for transducers which havelimited
`memory or size. Table 1 indicates the latest proposal for the
`P1451.4 compact-TEDS which will include parameters, such
`as bandwidth, which arecritical for higher bandwidth trans-
`ducers.
`Implementation. To take advantage of the results from the
`P1451 effort, P1451.4 will establish a standard that allows
`
`P1451.4 NCAP
`
`Figure 4. Ethernet-to-1451.2 NCAPcreated for a demonstration of con-
`cept (courtesy of Hewlett-Packard).
`
`analog-output mixed-mode transducers to communicate digi-
`tal information with a high-level IEEE P1451 object.
`
`if
`
`
`
`Table 1. Proposed IEEE P1451.4 TransducerElectronic Data Sheet (TEDS) measuring template formats.
`
`Field Description
`
`ROMPart
`Manufacturer
`Type number
`Versionletter
`Version number
`Serial number
`
`E2-PROM Part
`CRC8forthefirst 64+256 bits
`Selector of template descriptor
`Template identification
`Sensitivity @ Fyor
`Fret
`Calibration date
`Transfer function approximation
`F hpelectrical
`F Ip electrical
`F mounted resonance
`Mounted Q
`Temperaturecoefficient
`Sensitivity direction (x,y,z)
`Measurementposition ID (0... 511)
`Selector of extended template descriptor
`User data
`i
`
`Total numberof predefinedbits
`Total numberofbits
`
`Type
`
`Access
`
`# of Bits
`
`Bit Position
`
`Example
`
`Unit
`
`i
`
`Briel& Kjaer
`
`v
`
`
`
`Manufacturer
`UNINT
`Chrs5
`UNINT
`UNINT
`
`RO-Manuf.
`RO-Manuf.
`RO-Manuf.
`RO-Manuf.
`RO-Manuf.
`
`
`
`IEEE 1451.4
`M
`
`
`Accelerometer
`Vv
`
`CRC8
`SelOfDescriptor
`
`S(1 +n?
`S(1 +r)?
`date
`
`S(1 +r)?
`S(1 +71)?
`SCL +r)?
`S(t +r)?
`Si +r)?
`enum
`position
`SelOfExtDescript
`
`(n=0: section disabled)
`(n=0: section disabled)
`(n=0: section disabled)
`(n=0: section disabled)
`(n=0: section disabled)
`
`(User
`
`
`
`Vv
`
`R/W-all
`R/W-Cal.
`
`R/W-Cal.
`R/W-Cal.
`R/W-Cal.
`
`R/W-Cal.
`R/W-Cal.
`R/W-Cal.
`R/W-Cal.
`R/W-Cal.
`R/W-Cal.
`R/W-user
`R/W-Cal
`R/W-user
`
`184
`320
`
`Briiel & Kjaer
`1234
`
`0
`1234567
`
`TEEE 1451.4
`Acceleration
`100.0E-6
`10.0E+0
`July 18, 1997
`value from
`10.0E-3
`100.0E+0
`100.0E+0
`300.0E-3
`1.0E-6
`x=0,y=1,z=2
`
`User
`
`11
`27
`32
`39
`
`10
`
`34
`42
`
`58
`70
`82
`91
`99
`108
`110
`118
`120
`
`m/s?
`V/ms2
`
`Hz
`Hz
`Hz
`
`
`
`—_
`
`INSTRUMENTATION REFERENCE ISSUE
`
`25
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`

`

`
`
`
`
`
`
`
`
`eee
`Sa
`
`Briiel & Kjzer
`
`
`
`
`DS2435 1-Wire Port
`
`
`
`
`[2a Rx
`
`Figure 6. Exampleofpossible multi-drop smart transducer(courtesy of
`Briiel & Kjer).
`
`To normal
`Oneof the possible implementations is shownin Figure 3 —
`CCLDinput
`+5.V
`a multichannel P1451.4 NCAP, based on a 1451.2 NCAP,with
`
`optional multiplexer, data acquisition, logic or firmware for
`
`To
`TEDS extraction and conversion, as well as high-level P1451
`Gnd
`controller
`
`TEDS. Figure 4 shows a compatible 1451.2 NCAPcreated by
`Data
`Dallas
`Hewlett-Packard Co.* as a demonstration of concept.
`DS2430A
`
` B88 od ome sleevemols)
`
`
`es
`
`¥
`
`Figure 5. TEDS decoding with LabVIEW (courtesy of National Instru-
`ments).
`
`tb
`
`Compatibility with Legacy Systems
`P1451.4 transducers with TEDS will be compatible with
`legacy data acquisition systems by utilizing existing analog
`connections. Under normaloperating condition, P1451.4 trans-
`ducers will behavelike traditional analog transducers. Upon
`power-up or interrogation, P1451.4 transducers will enter a
`digital communication mode.
`Legacy systems can be updated to support P1451.4 transduc-
`ers, as follows:
`1. Hardware — Extra circuitry can be addedat the front-end to
`control the P1451.4 transducers and to decode the TEDS.
`This will require modification of the legacy systems.
`. Patch Panel — A patch panel can be used between P1451.4
`transducers andlegacy systemsto toggle powerto thetrans-
`ducersor send out interrogation signals to activate the digi-
`tal mode. It can also decode and uploadthe digital TEDS data
`to a controller. Additional hardware is necessary, but no
`modification of the legacy systems is required.
`. Firmware/Software — The embedded controller or the soft-
`ware in the legacy system can extract the TEDS data from
`the waveform memoryafter poweruporinterrogation. This
`solution requires no modification of legacy systems, nor ad-
`ditional hardware. Two previous demonstrations included
`a National Instruments LabVIEW® program with PC plug-in
`ADG(Analogto Digital Converter) cards (see Figure 5) and
`an IBASIC program with the HP35670A Dynamic Signal Ana-
`lyzer.
`
`w
`
`Current Approaches
`Several transducer manufacturers have supplied mixed-
`mode transducers with built-in intelligence for improvement
`suchasself identification. These updated mixed-mode trans-
`ducers utilize existing analog interfaces such as the ICP® and
`4-20 mA current loop interfaces with or without an additional
`digital connection.
`Several commercial mixed-mode smart transducersareavail-
`able. Members of the P1451.4 working group have proposed
`two types of implementation. Briiel & Kjzr has proposed a bi-
`directional, multi-drop communication scheme(see Figures 6,
`*Certain commercial products are identified in this article in order
`to adequately describe the proposed standard. Such identification does
`not imply recommendation or endorsement by the National Institute of
`Standards and Technology.
`
`
`
`ey
`3 Principle diagram of DeltaTron®
`
`epee OLY
`transducerintegrated with
`identificati
`Principle diagram of DeltaTron®
`ientification
`inputwith identification support
`
`Figure 7, Exampleof current implementation (courtesy of Briiel & Kjzr).
`
`Bus Master
`
`
`
`+5V
`47k
`
`iS
`RxTx
`
`
`
`
`5yA '
`100 Ohm
`2pia
`MOSFET
`
`
`DS2435 1-Wire Port
`
`
`
`Rx
`
`Tx
`8
`400 Ohm
`oa
`MOSFET
`
`
`4
`
`Figure 8. Coupling network between bus master(e.g., instrument) and
`1-wire port (e.g., transducer). Proposed by Briiel & Kjer.
`
`7 and 8). This proposal is based on standard MicroLAN® com-
`ponents from Dallas Semiconductor andthe digital communi-
`cation is activated by switching the normal(positive) supply
`current to a negative current. Other members have proposed
`point-to-point systems (such as shownin Figure 9). Digital
`communication is activated upon power-up (Kistler) or by a 2
`mA drop of supply current for a predefined time period
`(Endevco and Wilcoxon).
`Currently, the working group is very interested in the 1-wire
`MicroLAN®dueto its one wire nature and commercially avail-
`able components. Notein Figure 10 that the TEDS electronics
`does notincrease the size of a modal accelerometer.
`
`Future Development
`The P1451.4 working group has formed a TEDS subgroup and
`the subgroup hasachieved good progress. Hewlett-Packard and
`
`-
`
`26
`
`SOUNDAND VIBRATION/APRIL 1998
`
`
`
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`

`
`
`
`
`Analog
`
`
` H Digital
`
`Variable
`Current
`Supply
`
`t
`Current —
`|acees Nee :
`Change -
`Snes
`| Detector |
`Wilcoxon SmarTrans
`
`:
`
`Figure 9. Example of current implementations (courtesy of Wilcoxon
`
`SignalAnalysis System
`
`Research).
`
`
`
`
`|
`
`peatke
`O AC/DC and RS
`
`SooiyPai.
`
`Figure 10. The challenge of implementing TEDSin a modal accelerom-
`eter (courtesy of The Modal Shop).
`
`Kistler Instruments have agreed to provide licenses for their
`individual patents related to the P1451.4 working groupeffort.
`Dallas Semiconductorshas also agreed to provide a license of
`their patents related to the 1-wire MicroLAN®.
`Involvement by other companies with various sensing tech-
`nologies will be highly welcome.
`For more information on the P1451 working groups contact:
`Kang Lee, National Institute of Standards and Technology;
`Phone: 301-975-6602; e-mail: Kang.Lee@NIST.gov.
`
`Acknowledgments
`The authors would like to thank: Mark Buckner (Oak Ridge
`National Lab.), Jorgen Bakke (B&K), Stan Woods (Hewlett-
`Packard) and all the membersof the working group who have
`contributed to this work.
`
`Bibliography
`Chen,S., Poland, J., Liang, Z., Lally, R., “Smart Transducers,” Proceed-
`ings IMAC, 1993.
`Gierer,J., Grant, R., “Self Monitoring and Reporting Transducers,” Pro-
`ceedings Fourteenth Transducer Workshop, 1987.
`Talmadge, R., Appley, K., “Programmable Transducer Microchip Devel-
`opment,” Proceedings Sensors Expo, 1990.
`Eller, E., “An Accelerometer with Internal Self-Test and Identification,”
`Proceedings Sensors Expo West, 1990.
`Proceedings First IEEE/NIST SMARTSensorInterface Standard Work-
`shop, Gaithersburg, MD, 1994,
`Bryzek, J., et al, “Common Communication Interface for Networked
`Smart Sensors and Actuators,” SENSORS,pp. 14-23, September,
`1995.
`Brendel, A., “Sensor Stores Calibration Data in Nonvolatile ROM,”Test
`& Measurement,June 1996.
`West, R., “Automatic Calibration of Strain Gauges,” SENSORS, pp 44-
`46, July 1995.
`Gen-kuong,F,, and Johnson,R., “Accelerometer for High Frequency, Low
`Noise Application, with Self-Test/ID Feature,” 1990 Proceedings of
`Institute of Environmental Sciences(IES).
`van der Waal, E., Droinet, Y., Coransson, S., Tidy, S., “A Low Cost, High
`Performance Mixed Signal ASIC for the Calibration of Piezo-Resis-
`tive Sensors,” Sensors Expo West Proceedings, 1996.
`
`LA-5110, Circle 123
`27
`INSTRUMENTATION REFERENCE ISSUE
`
`
`CF-5200, Circle 122
`
`CF-1200, Circle 121
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