Interfacing Manual - Signature Technologies
Contents
1. _ DE IN USA SINATUA TECNOLOGIES INC COPYRIGHT 1997 AG PATENTS 4907529 5491647 LEDIG Channel 8 Channel 8 Gain Excitation Figure 7 A08 Jumpers Page 11 Interfacing Manual Jumper IN 1000X Jumper OUT 2X Channel 1 Gain Channel 2 Gain 10 Volts a papas h 1 3 Gai anne xcitation Papai ee 5 Volts Channel 2 Excitation Channel 4 Gain Channel 3 Excitation Channel 4 Excitation Saar ni i jitia d eTa p 4 R age pas pr p L A RE a iiia N ie 4 a af ae E IGHT 1997 SERIAL NO 7528 5491647 Figure 8 A D Input board jumpers Shunting the gage can reduce the signal from the High output gage For example The strain gage pressure sensors from Sensotec have the following spec 3mv v This terse statement translates to At full rated input pressure the output of the strain gauge bridge will be 3 Millivolts for every volt of D C excitation applied With a 10 volt excitation then the output of the Sensotec unit would be 30 Millivolts The ST system at high range only can stand only 5 Millivolts Obviously we ll overload the input 1f we try to put this much into the SA2000 input Reducing the excitation to 5 volts still gives us 15 Millivolts at full pressure so some other way of reducing the input voltage must be found The Bridge resistance is given as 350 Ohms Connecting a parallel resistance across the bridge is a good way of limiting the output of the bridge Th2. 4 Right Frort D 123456789 T l PTT LLL LE Toedo Commer uw Figure 23 Toledo Model 260 Interface Hookup to signatureA CE If the specific Load monitor you are using doesn t have grounded recorder return then the connection shown above to the Excitation on channel 1 should be removed The connecting cable from the Load monitor should be shielded and the shield should only be connected at the TEC end It s also generally a good idea to run a heavy bonding conductor between the computer chassis where the signatureACE is located and the Load Monitor Chassis Sometimes the Recorder Outputs will act as antennae for electrical noise and cause nuisance trips in the Load Monitor In this case if you trust the indications on the existing load monitor system calibration is a breeze since you can simply make the ST unit readout the same as the Load Monitor using the calibration utility described in the system user s manual Optionally you can install load cells and check calibrate both units Sensor Calibration If the sensor that you are attempting to calibrate comes with a statement of what the output of the device is in volts per unit of pressure or volts per ton etc then you can use that factor to generate calibration factors for the signatureACE SAMview system Page 25 Interfacing Manual Using the SENSOTEC pressure gage that we discussed back on page 11 we had at 10 volts exc
3. modifications to the TEC or SA2000 hardware may be needed which work can only be done by Signature Technologies personnel if the hardware warranty is to be preserved Page 5 Interfacing Manual Technical Information about the SA2000 TEC module combination The SA2000 Module is the engine that actually performs the data acquisition limiting I O control and network communications The TEC unit is an enclosed Printed circuit board assembly that provides connectivity for the external system elements signatureACE System common grounding considerations NOTE Signature Technologies Common points both Analog and Digital AND the Excitation points if SV excitation is selected are connected to EARTH GROUND The signatureACE system commons CANNOT be floated This means you ve got to be careful when connecting the signatureACE to a system that has a floating common like the Square D Press control systems In these cases the signatureACE common should be connected to Earth ground like the sheet metal of the control enclosure In most cases the wide Common mode range of the SA2000 will provide clean signals When you connect Analog inputs or Resolver inputs to the ST system even when you use the Hikes resolver converter connecting to the Excitation See note above or AGND signals to a system with a floating common will tie that floating common in the other system to earth ground and may
4. cause the existing system to malfunction In the case of the HiRes converter If you re not sure whether the resolver system you re connecting to has a floating common tie the AGND to EARTH GROUND probably the nearest handy screw in the chassis The common mode inputs of the HiRes converter will sort the signals out properly in spite of not having a good common reference Page 6 Interfacing Manual TEC Board Analog input SHIELD OA O she Ex I VAIL EX Do fAl Aot U Ab D SHIELD ood pooo0oC0oC ISS SSSSSSSSE IISY GSGISIGSYS Boo oooooooo Oo S S O SHIELD OIGA e SHIELD Ex OGA AL Ex DSa OA ABD D644 G gA AB DE K OAA Ex SENSORS Figure 1 TEC Input connections Differential Mode LO range 2 5 volts 1 A D count 1 22 Muillivolts Differential Mode HI range 0 005 volts 1 A D count 2 4414 Micro volts Auto Zero will take out D C offsets of up to 0 01 V D C at the input terminals Auto Zero occurs either When the clutch input to the SAM module is energized When the position input passes the software corrected ZERO position For Large step changes in the value of the offset while the machine is running more than one auto zero cycle may be required to null out the offset completely If the machine is stopped an analog clamp will deploy after 4 seconds and tie all inputs to Zero internally there is no change in the input impedance or loadin
5. has changed in the process Page 28 Interfacing Manual ae mem es ie se ee a a oe Pte Strain Strain oe Boe eae Soe ef Gages Gages ie eT rings i Figure 26 Combination Blank amp Draw load cell Calibratable In Fig 22 the design of the cell and the station have been altered to give a calibratable result There are strain gages both on the outer and inner diameters of the load cell and they are connected in parallel to cancel out the effect of force being thrown to the inside or outside of the cell body Also the complete force of the station flows through the cell without any assistance from other supports This cell requires much more wiring than the structure in Fig 21 but will more accurately indicate the forces form both operations Page 29 Interfacing Manual Topical Index 3 3 wire D C Proximity Switches Interfacing 21 4 4 20 ma current loop Interfacing cece 23 A A D Input board jumpers ccccccceeeeeeeeeseeeeeees 13 Acceptable offs t Vales ccsissteeestescmocien caceatintecuuetinds 14 Adjustment Strain Gage Output eeeeeeeeeees 12 Analog inputs TEC Board cccccccccscsessseeeeeees 7 Analog sensors Calibrating ccccccccccccsssssseeeeeees 23 C Calculation Shunt resistor value ccccsseseeseeeeees 13 Calibrating Analog sensors cssseeeeeeeeeeeeeeeeaes 23 Calibration of Home Made Sensors
6. used for Piezo devices are set to 5 volt excitation BEFORE hooking the sensors up Failure to do this can result in system damage Twinaxial Hookup Piezo Sensor Figure 15 Piezo Twinaxial sensor interfacing Preferred The Meg resistor R acts as a Drain to maintain the sensor at zero potential statically The Piezo sensor is then connected to the Signal inputs as shown and the gain of the channel is adjusted by shunting the input with the capacitor C What we re looking for is to limit the signal level to either 2 5 volts in LO Range or 0 005 volts in HI range selected by the jumper at the channel input In general it s better to run HI range as this minimizes the sag in the signature at lower speeds C Capacitor values in the 1 10 mfd range are normally required Coaxial Hookup Piezo Sensor Figure 16 Piezo Coaxial sensor interfacing Page 17 Interfacing Manual The illustration above at Fig 16 features a Twinax or two conductor shielded configuration such as would be used with InSitu Strip type sensors If you purchase from other sources a coaxial hookup will probably be supplied It s connected as shown in Fig 17 If your machine always runs fast then you could use the LO range fine for 200 S P M and up use capacitors in the 0 02 0 047 range to start and trim to suit If you flattop use a bigger capacitor If sag is
7. 2J Connection Stran LANK asserire ieu 1 Connections Sensor sereni ai 8 Correcting Excessive balance offsets cceeee 14 D Data Instruments Strain Links interfacing 17 Digital signals Interfacing ccccccseeeseeeeeeeeees 19 E EXCESSIVE Dalance Offsets 3 iaicsissssserseleosetisasavssiesiadiesaeass 14 G Grounding considerations cc eseeeeeeeeseeeeeeeeeeeeeeeeeaes 6 H Home Made Sensors Calibration ceee 27 I Interfacing 3 wire D C Proximity Switches 21 Interfacing Universal Proximity Switches 21 Interfacing 4 20 ma current loop cc eeeeeeeeeees 23 Interfacing D C Proximity Switches eee 21 Interfacing Data Instruments Strain Links 17 Interfacing Digital signals ccccccesseeseesseeeeees 19 Interfacing Pie ZO GeVICeS isis dvivesncnieinnastrencnni tus 17 Page 30 Interfacing Self amplified Analog sensors 22 Interfacing to existing Load Monitors ccccceee 25 Interfacing to Load Monitors seeeeeeeeeeeeeeeeeeees 23 MRO NUOTO E 5 J Jumper Locations SA2000 eeeesssssssssseseeeesssssssss 12 Jumpers A D Input board eeeeeessssesseeeeresssssssss 13 L Load Monitors Interfacing to ssssssssssssoooeeeeeeessssss 25 O Offset values Acceptable range ccceeseeeeeeeees 14 P Piezo devices Interfacing ysc6 ieil
8. 4 20 ma current loop to a voltage mode signal using a precision resistor to maintain calibration The 4 20 ma current loop will normally allow a certain amount of voltage to be generated without affecting to accuracy of the analog data Using the SA2000 input in LO range permits a peak signal of 2 5 volts 20 ma applied across a 100 Ohm precision resistor produces 2 volts of signal The circuit 1s SHIELD tEx citation T lt 12 Milliarmp Signal To 7 05 watt Current Loop Ta Excitation Figure 22 4 20 ma Current Loop Hookup The connection between Signal and Excitation is necessary if the 4 20 Ma current loop is floating to keep the signal inside the common mode range If the loop isn t floating and has one side grounded then you should break the connection between Signal and Excitation Calibrating Analog sensors for measurement Calculated In cases where the target for the Analog device is according to the test conditions in the manual and the target approaches perpendicular to the sensor and is parallel to it the figures in the sensor manual can be used to generate a theoretical calibration for the sensor Referring to the TURCK manual for the LIU series analog proxes Specifically the Ni8 M18 LIU the output of the sensor is 0 25 volts until the gap between the sensor and the target grows to 1 millimeter As the gap increases the voltage output grown to 10 volts
9. 51 gi a i 2400 Ohm 1 Excitation Ewent signal Trom Machine Figure 17 Relay Digital Input This is a simple method that would effectively interface with an existing event signal The relay coil is wired so that when the event occurs the relay is actuated The contacts of the relay are wired into one of the Channel inputs on the TEC module according to the labels as shown above Be sure to set the channel switch to LO position The channel should be set up with a calibration factor of 0 01 and a maximum of 25 I d set the limits originally at three for the yellow and 5 for the red Starting out with yellow and red both set at 2 degrees seems O K Set your window wide to begin with until you find where the digital signature occurs The signature will look like a rectangular wave going from 0 tons to 20 tons when the digital signal changes Page 19 Interfacing Manual Interfacing D C Proximity Switches to the signatureACE Proximity switches can be interfaced to the system to permit the signaturing of digital events pilot hole detection feed length confirmation etc Some external components are required as follows snieg NA 2 Common Figure 18 NPN type 3 wire D C Proximity switch Power Shield Shield Common Figure 19 P N P Type 3 wire D C Proximity Switch anec 2 Wire D C amp Universal Prox Signal Si
10. User Manual Appendix 9 Sensor Interfacing Guide For connecting Standard amp Non Standard Sensors To the SiIgnatureACE System Latest revision 8 20 99 SAMview MPMview SPCview FeatureView SA2000 SAM500 SAMnet InSitu FlexStrip andSmartSAM are registered trademarks of Signature Technologies Inc SignatureACE and Signature Technologies are registered trademarks of Signature Technologies Inc Dallas TX USA All other trademarks are the property of their respective companies Copyright 1995 1996 1997 1998 1999 2000 Signature Technologies Inc All Rights Reserved No part of this publication may be reproduced via any means print electronic or other without the written permission of the publisher Printed in the USA Signature Technologies Inc 13375 Stemmons Fwy 320 Dallas Texas 75234 USA Telephone 972 488 9777 Fax 972 488 2924 Website lwww signaturetechnologies com Interfacing Manual Page 2 Interfacing Manual Table Of Contents MIN RONU IN acest cea eececaerctes eet et vsermcscel acca act oaecc eas aceasta ais nae cieusatcave tare inte acaietoacianhe a atoe anette aie 5 Technical Information about the SA2000 TEC module combination cece ec eececeeees 6 Page 3 Interfacing Manual Table of Illustrations Page 4 Interfacing Manual INTRODUCTION The signatureACE system hardware is specifica
11. a problem try increasing the value of the 1 Meg resistor Some channels of the SA2000 will have less leakage current and can be used with values as high as 10 Megs other channels can t You ll have to find this out for yourself The 1 Meg value works for every channel Use a good quality capacitor Polyester type to limit leakage Don t use electrolytic or Tantalum capacitors Interfacing Digital signals to the signatureACE Digital signals can be brought into the signatureACE and displayed limited just like analog signals You must take a couple of things into consideration though The AUTO ZERO function will make whatever state the digital signal 1s in at Top Dead Center zero degrees to be ZERO If the signal is HIGH at Top Dead Center it will be displayed as a rectangular wave dropping to 2048 from Zero when it goes LOW when the calibration factor is set to 1 If the signal is LOW at zero degrees it will be displayed as a rectangular wave jumping to 2048 when it goes high The AUTO ZERO function can be disabled selectively through the use if the INP files Contact ST for more information about this if needed If the AUTO ZERO function on a channel is disabled the result will be a rectangular wave jumping between 2048 to 2048 on the screen with the calibration factor set to 1 Page 18 Interfacing Manual A simple way to interface digital On Off signals to the ST system SHIELD r tee citation Y
12. at 5 millimeters of gap With the resistive divider as described above installed the 10 volt signal becomes 2 48 volts and the 25 volt signal becomes 0 062 volts Let s say we want to calibrate this sensor to read out in relative thousandths of an inch Imm 0 03937 5mm 0 19685 so the difference is 0 15748 The voltage output goes from 0 062 to 2 48 over this range so the voltage difference 2 418 The ST system has a sensitivity of 1 A D count for each 0 0012213 Volts in LOW range Page 22 Interfacing Manual 2 418 0 0012213 1979 counts equals a displacement change of 0 15749 or 159 5 thousandths 157 5 1979 0 079586 which is the thousandths calibration factor for the ST system 4 1979 0 002021 is the Millimeters calibration factor Experimentally developed If the target is not per the test criteria but the approach is perpendicular and parallel then the calibration must be arrived at experimentally Follow the detailed procedure Step 1 Step 2 Step 3 Step 4 Step 5 Step 6 Step 7 Step 8 Step 9 Step 10 Step 11 Go to Samtest Select gauge selection 2 Turn OFF the auto zero for the analog prox channel Make sure the display for the channel is in counts Put a sheet of heavy paper over the sensor Apply the target to the sensor thru the paper Note the reading on the screen Add another piece of paper Note the reading on the screen Repeat for 7 8 addi
13. case the calibration is only valid for force applied in a SPECIFIC WAY Page 27 Interfacing Manual sah ae SGP at aAC MaMa PTA NaGRS SS OAGRG a sence SISS ae Loe ee eee eee ee eee ee FTE Ti ras ess SSN 5 m aaarnas WORKPIECE Figure 25 Combination Blank amp Draw load cell Uncalibratable The illustration above is for a combination blank and draw station In this case the Blanking takes place on the outer circumference of the draw ring while the draw takes place down the middle The cell is located such that the inner diameter of the draw punch is in line with the gauging location while the blanking portion is more in line with the outside diameter of the load cell Force tends to flow straight from its source to the place where the support occurs The force required to draw and the force required to blank will reach the gages in the load cell differently and will not produce the same effect If the load cell is calibrated for the drawing force the blanking force will indicate MUCH lower than it actually is since it flows through the outer diameter of the load cell and the support block Alternatively if the load cell is calibrated for the blanking force the Draw force will show MUCH higher that it actually is since it flows directly through the gauging location This cell design in short can t be calibrated accurately for both operations but can function comparatively so that you can tell that something
14. e Calibration of homemade sensors you must make sure of the following You must make sure the sensor is calibratable There are cases where a sensor may not be calibratable due to the way force flows to it In general if ALL the force involved in a die part can be made to flow directly through a load cell and then calibration is possible Page 26 Interfacing Manual caper Sanaa ae Foo BES p i Tina ote ia Tri HTE pom Figure 24 Extrude station load cell calibratable The example above is for a station that extrudes a hole in the bottom of a cup The Extrude punch is mounted in line with and directly below the punch itself The force in the punch flows exclusively through the load cell In order to calibrate this cell a calibrated force possibly from a hydraulic press should be applied to the cell just as it would be when the cell is mounted in the die Differences in surface finish of the tool elements that contact the cell can change the concentrations of force through the cell We would recommend that the actual components are used 1 e place the load cell on the backing surface it will have in the die and apply pressure with the extrude punch Following the instructions for calibration in the user s manual apply the force calibrate and then apply the force several more times as a check On the other hand sometimes the force flows both through the cell and through the matrix of the die as well In this
15. e way to calculate the shunting resistor 1s Where R the strain gage bridge resistance in Ohms Att the reduction factor desired Sh the value of the shunt resistor in Ohms Sh l S a k Att F Figure 9 Shunt resistor value calculation Page 12 Interfacing Manual In the case above I d like to run at 10 volts excitation but I d have 0 030 volts of output and I need to get down to 0 005 volts for a proper input I need then to cut the signal from the sensor to 1 6 of what it normally is This is a reduction factor of 0 16666 The gage resistance is 350 Ohms Example l Sh ee can em ee 350 0 1666 250 l Fy o GA 200 l TTT a 00171497 0002057 Sh 0 014292 6a OF Ghims Sh A shunt resistor of 69 97 Ohms use the 0 1 resistor value of 69 8 Ohms connected in parallel with the strain gage bridge across the amp Signal inputs will achieve the proper reduction of the gage output Dealing with excessive balance offsets When dealing with strain gages that have static offset voltages a voltage present between Signal and Signal when under no load which is due either to basic gage imbalance or due to a significant mechanical pre load on the gauged component in its resting state There must be some care taken to avoid Railing the input amplifier on the SA2000 The Auto Zero circuit will always successfully bring the input level down to zero BUT if the input amplifie
16. g when the analog clamp deploys Page 7 Interfacing Manual Standard Sensor Connections The normal sensor for use with the signatureACE system is a pre packaged Strain LINK The strain link is normally a simple Whetstone bridge having two of its four elements mounted in such a way that they are IN LINE with the stress in the measured machine element The other two are mounted ACROSS Perpendicular to the direction of the stress 100 000 3 Pounds Force Foissoan effect cross section growth 0 28 0 33 8 Strain Figure 2 Stress Strain Poisson s ratio illustration Fig 2 illustrates the physical effect of STRESS on a column of material Starting with two identical columns STRESS is applied to one of them j Higher Resistance f Lower Resistance Figure 3 Strain Gage illustration Page 8 Interfacing Manual The STRESS produces a dimensional change in the column that is called STRAIN It also causes the stressed column to Bulge or increase its cross section This growth in cross section is referred to as the Poisson effect As shown in Fig 4 the strain gage element is a series of columns connected in series electrically As the machine to which the strain gage 1s attached changes its length the strain gage changes along with it Under compression the gage columns grow shorter but thicker This growth in cross section with reduced length red
17. gnal Excitation Figure 20 Hookup for 2 wire universal Proximity Switch Page 20 Interfacing Manual Interfacing Self amplified Analog sensors to the signatureACE Analog proximity switches like the Turck type LU illustrated or other self amplified sensors Pressure sensors temperature sensors etc can be interfaced to the SA2000 Module Two things must be considered First is the input voltage requirement of the sensor In the case of the Turck unit illustrated 15 volts D C is required Since the available excitation voltage is only 5 or 10 V D C you must provide an external power supply for the sensor Second the output voltage range of the sensor must be considered The Turck according to its specifications swings from about 0 5 volt to 10 volts 15 Volt Power N Browr supply Power Shield Excitation sg Turck LU Series Analog Prox Comman Figure 21 Analog Proximity hookup Since the input of the SA2000 can only tolerate 2 5 to 2 5 volts some attenuation of the Turck signal is necessary The resistive divider shown reduces the 10 volt swing of the Turck down to 2 48 volts into the SA2000 R1 R2 13300 Ohms E 10 volts I E R 10 13300 0 000752 Er2 Ir2 R2 0 000752 3300 2 4816 Page 21 Interfacing Manual Interfacing 4 20 ma current loop to the signatureACE system This is done by converting the
18. ine structure The connections for these links are fairly standardized Page 9 Interfacing Manual For the Toledo T400 LINK or HELM HT400 links the hookup for Compression sensing as would be found in the connections Pitmans of a punch press 1s as illustrated below in Fig 5 Under Compression Connection Mounting aa Escitation Inline 2 s4 F Across Signal at le RED i Si0nal Fo _ ted HT gy eee or fe ys Across 2 SHIELD Figure 5 Standard Strain Link Hookup Compression Under Tension Upright Mounting aa Excitation GREEN e co a x a ee BOnISS TTS s Inline 2 S1gnal nia ey Se PE y WHITE a oa ne Signal ei wes RED eed oe Inline 1 es YAA Across 2 a re l 4 Excitation BLACK 7 SHIELD Figure 6 Standard Strain Link Hookup Tension Page 10 Interfacing Manual For Tensive sensing the signal wires are simply flipped as illustrated in Fig 6 above Data Instruments Strain links are amplified units that require a totally different hookup as illustrated in Fig 10 later in this publication If you don t have colors as illustrated above or just don t remember the code you can generally perform checks on strain links with an Ohmmeter to find out what the internal connections are There will be two pairs of wires that have higher resistance than any other pair Generally you can hook the excitati
19. ions eesstee van eatieeeks 17 S SA2000 Jumper Locations ccccccceeeeeeeeeeeeeeeeeees 12 SA2000 Technical Info ccc cececcescescsceees 6 Self amplified Analog sensors Interfacing 22 Sensor Calibration strain gage type ccceeeeeeeeeeees 26 Sensor Connections 1333 ede as shee ees 8 Shunt resistor value calculation cccccceccecceceeees 13 Standard Sensor Connections ccscescecceccecescesceces 8 Strain Gage output adjustment cc cceeeeeeeeeeees 12 strain gage sensor Calibration ccccccccceeeseeeeeeees 26 Stran Link HOO kUPsenser a ek dooce tiusneant 11 T Table Of Contents ccc ccc ccc eccesccsccecceccescescescees 3 Table of Illustrations cccccceececceccscescecceccscescescess 4 Technical Info SA2000 TEC ooo cee eeeeee 6 TEC M echnical TM O raen oreo loees erecta 6 TEC Board Analog input cccccccssssssseeeeeeeeeeeees 7 U Universal Proximity Switches Interfacing 21 W Whetstone Bridge connection 0eeseseeeeeeeeeeeeees 10 Interfacing Manual Page 31 Interfacing Manual Contact us with any questions at Signature Technologies Inc 13375 Stemmons Fwy Ste 320 Dallas TX 75234 Phone 972 488 9777 FAX 972 488 2924 Website www signaturetechnologies com Page 32
20. itation 30 Millivolts of signal at SOOO P S I We then shunted the gage to get its signal down to a usable level of 5 Millivolts at 5000 P S I The calibration factor will be calculated as follows The SAM gives one A D count for each 0 002441406 volts of input With a 5000 P S I input to the gage the signal to the SA2000 will be 0 005 volts The SA2000 multiplies the signal X 1000 and passes 5 volts to the SAM module The 5 volts will create 2048 A D counts 5 volts divided by 0 002441406 volts per count 2048 counts 2048 A D counts 5000 P S I The Calibration factor 2 441406 S000 P S I divided by 2048 counts When this factor is programmed into the channel used by the Pressure sensor the signature will display the value in calibrated P S LG On the other hand the Analog prox couldn t be calibrated by the signatureACE system since it s characteristic is non linear and the SAMview display package is not set up to provide programmable offsets or sunken zero points 0 1 mm distance is 0 3 volts 1 5 mm increases linearly from 0 3 to 10 volts With a characteristic like this there s no way to get the system to read out in mm directly The best that could be done is to read out in voltage and develop the distance with a chart If direct readout in mm was required software could be written to perform that conversion Contact ST for details Calibration of Home Made Sensors In cases where you are attempting th
21. llel resistor combinations are used be sure to SOLDER all the joints Inexpensive resistor assortments can be obtained from your local Radio Shack electronics shop Page 15 Interfacing Manual NOTE If you apply balancing resistors to a commercial load cell to correct an out of balance situation you will alter the calibration values for the cell requiring an experimental calibration to be performed if calibrated values are needed Interfacing Data Instruments Strain Links COMPRESSION Hookup gt rrr Signal een ie ai URS OT TENSION Hookup Data Instrurnents ee A ae San ace Strain Li Bloc Figure 14 Data Instruments Strain Link Hookups Data Instruments links are fundamentally different that other links since they have a built in amplifier Since DI links operate on 5 V D C excitation the Excitation of the SA2000 MUST be reduced to 5 Volts BEFORE the DI units are connected Failure to do this will permanently damage the DI strain links This hookup is for compressive application as would be experienced on the Connections Pitmans of a press For Tensive application swap the Green and White wires NOTE Since the DI link is self amplified the gain switch on the SA2000 Unit must be set to LO position on DI link inputs Interfacing Piezo to the signatureACE system Piezoelectric transducers like IMCO HELM Load Plugs or load probes or Kistler Piezo load sensors or Accelerometers
22. lly designed to operate with resistive strain gages in full Whetstone bridge configuration To this end we supply precision regulated D C excitation voltage and full floating differential signal input We also provide sufficient amplification of the strain gage signals so that dimensional changes as low as 30 uStrain yield usable signatures Sensor inputs are brought into the TEC unit and hooked to the terminals on the Green printed circuit board in the TEC enclosure This board is a passive connection device with a few indicators and a fuse tester NO signal processing is preformed The TEC can be mounted up to 100 feet from the SAM module Our standard preferred bridge resistance is 350 Ohms but we can excite and use gages of virtually any resistance Our standard excitation levels are 10 V D C and 5 V D C They are jumper selectable Each individual channel can be configured to the desired excitation level Each input channel can be individually selected to either HIGH or LOW range HIGH range provides an amplification of 1000X that is used for Strain gage inputs LOW range is a 2X amplification that is used for interfacing high level signals Often the user wishes to interface various other types of devices into the system This publication is submitted for the purpose of instructing the user on the proper methods and additional components that may be required for successful operation of other types of input devices In some cases
23. on to one of the high resistance pairs and take the signal from the other pair Strain links typically don t have compensation components so they don t care how they re connected In the case of high precision load cells there are normally compensation components that make it necessary to connect to the proper sets of wires to get accurate results If you don t have the information call the cell manufacturer If the Strain Gage output is too high for the ST system Since the signatureACE doesn t have any provision for input gain adjustment outside of the 1000X 2X gain switch sometimes the output of a strain gage bridge in highly strained applications can exceed the input range of the SA2000 in HI range One way of cutting the output of the Strain gage is to reduce the excitation voltage from 10 volt to 5 volts with the switch provided for that purpose This is a valid way of cutting the input level down to 0 5 times its 10 volt value This is good if you have a lot of signal the noise level will be significantly increased on the lower level signals Jumper Locations on the SA2000 Channel 1 Channel 1 Excitation GROUND TTIE Midd ij Gi UGT aii i a 5000900000008 REREN x 00 00 coo ra as y r 4 N K e D gt gt 3 s J a gt a x Rs e lhl e on ea A gt f To gt 50 0090 7 SSO 000000000099 S Bs bi F re fi i y R i Y S d O f ECE 1T9 020 5001 SERIAL NO _
24. ow 0 1 pattern male header that carries the signals The bottom row of pins is all grounded and can be connected directly back to the Excitation point on the signatureACE The Toledo Analog Track Outputs are numbered as follows Channel 0 Outer Slide Total Total for S A Machines Channel 1 Outer Slide Left Rear Left Rear for S A Machines Channel 2 Outer Slide Right Rear Right Rear for S A Machines Channel 3 Outer Slide Left Front Left Front for S A Machines Channel 4 Outer Slide Right Front Right Front for S A Machines For 8 channel units additionally Channel 5 Inner Slide Total Channel 6 Inner Slide Left Rear Channel 7 Inner Slide Right Rear Channel 8 Inner Slide Left Front Channel 9 Inner Slide Right Front In general the recorder outputs are available on any of the commonly available load monitor units and the hookup is identical to the one shown above except that the method of connection is probably going to be different HELM uses double circuit 1 4 Phone jacks Data Instruments uses Phoenix plug in terminal strips One side of the signal is usually grounded Refer to the manual for the Load Monitor you have for the connections Page 24 Interfacing Manual Toledo Charnel 07 TOTAL k Toledo Channel 1 Lett Rear TOE ST sa FO E sl Toledo Channel 2 Right Rear Toledo Channel 3 Lett Front Toledo Channel
25. r which is outside the Auto Zero loop is saturated there will be NO signature Excessive imbalance in a strain gage is not a serious problem with the gage and 1s quite common when gages are bent around a circular load cell structure or applied to an uneven surface Acceptable offset values In HIGH range the static offset voltage should be LESS THAN 0 004 volts 4 Millivolts AND more than 0 003 volts 3 Millivolts for FULL RANGE capability Page 13 Interfacing Manual In LOW range the static offset voltage should be LESS THAN 1 75 volts AND more than 1 0 volts for FULL RANGE capability How to diagnose remedy the situation The best way to see whether the gage is throwing too much offset at the SA2000 is by applying a millivoltmeter Like a Fluke Digital multimeter which has a 300 Millivolts scale across the Signal plus probe to Signal Negative probe leads and measuring the static voltage Excitation Signal TEC Unit Millivolt Meter ayes 2 Figure 10 Gage out of balance AS stated above in HIGH range 1f the static offset is larger than 4 millivolts or less than 3 millivolts then it s too far out and must be brought in with balancing resistors The best way to bring the offset down is a Connect the meter as above to the Signal and Signal terminals b Hook a resistor of 100K ohms between ANY Excitation connection Either or and ANY Signal Ei
26. require a different technique than Strain gages The Piezo device is a self generating sensor that produces energy that 1s proportional to deformation of the Piezo element Note that I used the word ENERGY not current or voltage The Piezo device will produce a certain amount of energy when it is squeezed but will also extract the same amount of energy when it is released What is required to properly see the output of a Piezo device is a Charge Amplifier which can be formed by connecting a capacitor across the and Signal inputs of the TEC module There is some belief that a Piezo device is Rate Sensitive 1 e they produce a greater output when squeezed quickly than they do if squeezed slowly In fact they don t It is the leakage of the Charge amplifier that creates the Rate Sensitivity not the sensor A High quality Charge amplifier shows little difference related to Rate of change Page 16 Interfacing Manual The signatureACE input is not Instrumentation grade but is superior to most front ends due to its low leakage and high amplification enabling the use of large capacitive loads to store the charge from the sensor When a Piezo device is connected to the TEC Unit some external components are required as illustrated below First the Piezo signal must be centralized in the common mode range of the input amplifier The connection shown from Excitation to Signal accomplishes this MAKE SURE the SA2000 inputs
27. ther or connection 10 Excitation Signal Figure 11 Resistor hooked the wrong way error larger Page 14 c When the resistor is connected the offset will either get better or worse Interfacing Manual d Ifit gets worse try the hook the resistor to the OTHER Excitation connection Verify that the offset gets better when the resistor 1s applied If the voltage goes from a POSITIVE value to a NEGATIVE value or vice versa the resistor connection is right but the resistor value is too low 7 100K Excitation Shield som tt sga h Eein JEG Unit Millivolt Meter etl i i D D Figure 12 Resistor hooked the right way error less but resistor too small e Then adjust the resistor value by applying LARGER resistor values for LESS effect or lower resistor values for more effect The aim is to get the offset close to zero volts within the values given above Fine adjustments can be made by using parallel or series combinations of resistors 150K Excitation Signal Millivolt Meter ene 2 2 a Figure 13 Balance within acceptable limits f Finally permanently install a fixed resistor or resistor combination of the proper value Signal permanently across the same points The most practical way to do this is to clamp the resistor leads in the terminals and solder the Strain gage wires to the resistor If series or para
28. tional pieces of paper Measure and note the paper thickness Plot the points that you developed Vertical scale is the output of the sensor as displayed on our system in counts Horizontal scale is the thickness of the paper stack that resulted in the readings If the plot is a straight line you re home free If it s not straight make the best estimation of a straight line that averages the differences by eye Then take the difference between the thinnest and thickest stack in counts Take the dimensional difference between the thinnest and thickest stacks in thousandths of an inch Divide the dimensional difference by counts That will be your thousandths calibration factor Worked Example The paper is 0 01 thick Page 23 Interfacing Manual With one piece of paper you got 1023 counts With 9 pieces of paper you got 593 counts There s 80 thousandths difference between 1 sheet and 9 sheets There are 430 counts of difference between 1 sheet and 9 sheets 80 430 0 18605 the thousandths cal factor for that sensor Note The channel will read out relative units not actual dimensions Interfacing to existing Load Monitors Sometimes you may want to connect the signatureACE unit downstream of an existing load monitor In general the load monitors have Recorder or Track outputs available Also in general one side of the output will be GROUND On the Toledo units there is a double r
29. uces the electrical resistance of the element The strain link bar that is being gauged is also experiencing this Poisson effect under compression the bar become shorter but increases cross section normally 0 285 times Strain dimensional change for Steel The gage element mounted perpendicular to the stress will respond to this dimensional change by going into tension i e getting longer but reducing its cross section This Across gage will increase its resistance with conversely the gage element mounted perpendicular to the stress When these gage elements are connected together as shown below Under Compression EXL i ION Inline 2 Ne ye ross F E TE f _ SILNAL r Fa Fa rea Fia SIGNAL e fae os aF g P z ON Ea eres BE Piafi 1 u E J ACOS S Reo g 7 os Inline 1 ESCITATIOMN Figure 4 Whetstone Bridge connection A full Whetstone bridge is created Under compression the gage elements IN LINE with the stress application will REDUCE their resistance while the elements perpendicular to the Stress application will INCREASE their resistance Since the gage elements are reversed on each side of the bridged under compression the Signal terminal will move in a positive direction while the Signal terminal will move more negative There will then be a differential between the and Signal terminals which is then fed to the signatureACE system as an input of the force in the mach
Download Pdf Manuals
Related Search