4WFBS120, 4WFBS350, 4WFBS1K 4 Wire Full Bridge Terminal Input Modules Revision: 3/12

Transcription

1 4WFBS120, 4WFBS350, 4WFBS1K 4 Wire Full Bride Terminal Input Modules Revision: 3/12 Copyriht Campbell Scientific, Inc.

2

3 PLEASE READ FIRST About this manual Please note that this manual was oriinally produced by Campbell Scientific Inc. (CSI) primarily for the US market. Some spellins, weihts and measures may reflect this oriin. Some useful conversion factors: Area: 1 in 2 (square inch) = 645 mm 2 Lenth: Mass: Pressure: Volume: 1 in. (inch) = 25.4 mm 1 ft (foot) = mm 1 yard = m 1 mile = km 1 oz. (ounce) = lb (pound weiht) = k 1 psi (lb/in2) = mb 1 US allon = litres In addition, part orderin numbers may vary. For example, the CABLE5CBL is a CSI part number and known as a FIN5COND at Campbell Scientific Canada (CSC). CSC Technical Support will be pleased to assist with any questions.

4

5 4WFBS120, 4WFBS350, 4WFBS1K Table of Contents PDF viewers: These pae numbers refer to the printed version of this document. Use the PDF reader bookmarks tab for links to specific sections. 1. Function Specifications Measurement Concepts Quarter Bride Strain Quarter Bride Strain with 3 Wire Strain Element Quarter Bride Strain with 3 Wire Element Wirin Quarter Bride Strain with 3 Wire Element Wirin usin a multiplexer Quarter Bride Strain with 3 Wire Element Calculations Quarter Bride Strain with 3 Wire Proram Examples CRBasic Prorammin Edlo Quarter Bride Strain with 2 Wire Element Quarter Bride Strain with 2 Wire Element Wirin Two Wire ¼ Bride use with Multiplexers and Equations Quarter Bride Strain with Dummy ae Quarter Bride Strain with Dummy aue Wirin Setup Quarter Bride Strain with Dummy aue Calculations Quarter Bride Strain with Dummy aue Example Prorams Quarter Bride Strain Lead Resistance Compensation Mathematical Lead Compensation for 3-Wire, ¼ Bride Strain Mathematical Lead Compensation Circuit and Equations Mathematical Lead Compensation Prorams Shunt Calibration Lead Compensation for 3-Wire, ¼ Bride Strain Three Wire ae Circuit with Shunt Math for Shunt Calibration of 3-Wire, ¼ Bride Strain Circuits Example Prorams for Shunt Calibration of 3-Wire, ¼ Bride Strain Circuits Lead Compensation usin Quarter Bride Strain with 2 Wire Element Calculation of Strain for ¼ Bride Circuits...37 i

6 4WFBS120, 4WFBS350, 4WFBS1K Table of Contents Fiures Table 1-1. Terminal Input Module with CR Schematic Strain definition Three wire quarter bride strain circuit wire ¼ bride strain wirin wire ¼ bride strain with multiplexer wirin Two wire quarter bride strain circuit Wirin for 2-wire aues Quarter bride strain circuit with dummy aue ¼ bride strain with remote dummy aue ¼ bride strain with dummy aue at dataloer Three wire ¼ bride strain circuit Shuntin remotely across active aue Circuit for shuntin across dummy resistor Wirin for shunt across dummy resistor Two wire quarter bride strain circuit Strain ae in full bride Input Locations Used in CR10(X), 21X, and CR7 Examples ii

7 4WFBS120, 4WFBS350, 4WFBS1K 4 Wire Full Bride Terminal Input Modules (TIM) 1. Function The 4WFBS120, 4WFBS350, and 4WFBS1K Terminal Input Modules (TIM) complete a full Wheatstone bride for a sinle strain ae or other sensor that acts as a sinle variable resistor. The difference between the three models is in the resistor that matches the nominal resistance of a 120 ohm, 350 ohm, or 1000 ohm quarter bride strain ae. It can also be used to complete the back half of a Wheatstone bride for use in a ¼ bride strain circuit (1 active element) usin a dummy ae, or in a ½ bride strain circuit (2 active elements). 2. Specifications FIURE 1-1. Terminal Input Module with CR1000 2:1 Resistive Divider Resistors: 1 kω/1 kω Ratio 25 C: ±0.01% Ratio temperature coefficient: 0.5 ppm/ C (-55 C to 85 C) Power ratin per element: C Completion Resistor: 120, 350, or 1000 Ω 25 C: ±0.01% Temperature coefficient: ±0.8 ppm C -1 (-55 C to 85 C) Power ratin: C 1

8 FIURE 2-1. Schematic 3. Measurement Concepts Measurin strain is measurin a chane in lenth. Specifically, the unit strain ( ε ) is the chane in lenth divided by the unstrained lenth ( ε = Δ L / L), and thus is dimensionless. L T + Δ L T L L T P P L + Δ L FIURE 3-1. Strain definition As the subject is elonated in the lonitudinal direction, the material will be narrowed or thinned down in the transverse direction. The ratio of the transverse strain to the lonitudinal strain is known as the Poisson ratio (ν). ν = ΔLT L ΔL L T 3.1 This Poisson ratio is a known property for most materials and is used in some half bride strain and full bride strain circuits. Strain is typically reported in microstrain ( με ). Microstrain is strain expressed in parts per million, i.e.: a chane in lenth divided by one millionth of the lenth. A metal foil strain ae is a resistive element that chanes resistance as it is stretched or compressed. The strain ae is bonded to the object in which strain is measured. The ae factor, F, is the ratio of the relative chane in resistance to the chane in strain: F = Δ R / R Δ l / l. For example, a 2

9 ae factor of 2 means that if the lenth chanes by one micrometer per meter of lenth ( 1με ), the resistance will chane by two micro-ohms per ohm of resistance. A more common method of portrayin this equation is: Or in terms of micro-strain: ε = με = ΔR F R ( 1 10 ) 6 ΔR F R Because the actual chane in resistance is small, a full Wheatstone bride confiuration is used to ive the maximum resolution. The Wheatstone bride can be set up with 1 active ae (Quarter bride strain circuit), two active aes (Half bride strain circuit), or 4 active aes (Full bride strain circuit). For each of these Wheatstone bride circuits there are multiple confiurations. The 4WFBS module provides three resistors that can be used for three of the arms of the Wheatstone Bride (Fiure 4-1). There are two 1000 ohm precision resistors for the back plane of the Wheatstone bride, and a resistor matchin the strain ae's resistance for the bride arm opposite the ae. The inputs of the 4WFBS are confiured so that this matchin resistor can be bypassed if it is desired to utilize a dummy aue, or to use two active aues (Half Bride Strain circuit). For Full Bride Strain circuits, as all four arms of the Wheatstone bride are active aes, there is no need for completion resistors, and thus a 4WFBS module is not required. The resistance of an installed ae will differ from the nominal value. In addition, lead resistance imbalances can result in further unbalancin of the bride. A zero measurement can be made with the ae installed. This zero measurement can be incorporated into the dataloer proram such that subsequent measurements can report strain relative to this zero basis point. This removes the apparent strain resultin from the initial bride imbalance. Strain is calculated in terms of the result of the full bride measurement. This result is the measured bride output voltae divided by the bride excitation voltae: V out / V ex. All of the various equations that are used to calculate strain use V r, the chane in the bride measurement from the zero state: V = ( V / V ) ( V / V ) r out ex Strained out ex Zero 3.4 The result of the zero measurement, ( V / ) out V ex Zero, can be stored and used in the calculation of future strain measurements. Alternatively, the zero readin value can be left at 0 (zero measurement is neither recorded nor used). It should be noted the actual result of the full bride instruction (BrFull) is the millivolts output per volt of excitation (1000 V / V ). The StrainCalc out ex 3

10 4. Quarter Bride Strain function used in CRBasic uses this raw output as its input to calculate µstrain. See Section 4.5 Calculation of Strain for ¼ Bride Circuits for a detailed derivation of the equations used. A "quarter bride strain circuit" is so named because an active strain ae is used as one of the four resistive elements that make up a full Wheatstone bride. The other three arms of the bride are composed of inactive elements. There are various circuits that use a sinle active element, includin 2-Wire aues, 3-Wire aues, as well as a few circuits that utilize a dummy aue for the arm opposite the arm holdin the active ae instead of a resistor, R D in Fiure (See Fiures 4.3-1, 4.3-2, and 4.3-3). The 4WFBS TIM modules can support all types of these ¼ Bride Strain circuits. 4.1 Quarter Bride Strain with 3 Wire Strain Element A 3-wire quarter bride strain circuit is shown in fiure Strain aes are available in nominal resistances of 120, 350, and 1000 ohms. The 4WFBSXXX model must match the nominal resistance of the ae when usin the 3-Wire circuit (e.., the 4WFBS120 is used with a 120 ohm strain ae). In Fiure 4.1-1, R 1 and R 2 are 1000 ohm resistors makin up the back plane of the Wheatstone bride, as is done in the TIM desin. R D, the third resistive element, is the complementary resistor that has a nominal resistance of the unstrained ae. The 4 th resistive element is the active strain ae. R 2 =1 KΩ R D Excite V - + L 3 R 4 = aue R 1 =1 KΩ L 2 L 1 FIURE Three wire quarter bride strain circuit The 3-Wire ae alleviates many of the issues of the 2-Wire ae. As can be seen in Fiure 4.1-1, lead wire L 3 is in the arm of the Wheatstone bride that has the completion resistor while lead wire L 1 is in the arm that has the active ae. L 2 is tied back to the input channel of the dataloer that has an input resistance reater than 1 ohm, thus the current flow is neliible, neatin effects of L 2 s resistance. This circuit nulls temperature induced resistance chanes in the leads as well as reduces the sensitivity effect that the wires have on the aue. See Section 4.4 for more on Lead resistance effects and methods to compensate for them. 4

11 1 N O 4WFBS120, 4WFBS350, 4WFBS1K 4 Wire Full Bride Terminal Input Modules (TIM) Quarter Bride Strain with 3 Wire Element Wirin Fiure illustrates the wirin of the strain ae to the 4WFBS module and the wirin of the module to the dataloer. It is important that the ae be wired as shown, and that the leads to the L and terminals be the same lenth, diameter, and wire type. It is preferable to use a twisted pair for these two wires so that they will undero the same temperature and electromanetic field variations. With this confiuration, chanes in wire resistance due to temperature occur equally in both arms of the bride with neliible effect on the output from the bride. Dataloer VX or EX 4WFBSXXX TIM Shunt Receptacle H L A R2 =1KΩ R1=1KΩ RD Active aue or Shunt Receptacle FIURE wire ¼ bride strain wirin Quarter Bride Strain with 3 Wire Element Wirin usin a multiplexer When usin a mechanical relay multiplexer such as the AM16/32B, the 4WFBS module should normally be placed on the face of the multiplexer similar as shown in Fiure WFBS AM16/32B Relay Multiplexer H L H L H L H L H L RES CLK ND 12V 4X16 COM 7 EVEN ODD 13 H L H L H L 2X32 CR10X CR23X CR1000 CR3000 CR X CR7 CR800 CR H L H L H L H L H L A E1 E3 EX1 EX4 EX1 EX3 or VX1 VX3 VX1 VX4 EXCITATION SWITCHED EX1 EX2 or 1 4 ANALO OUT VX10VX2 1L 1L 1L 1L 1L 1L 1L 1H 1H 1H 1H 1H 1H 1H CR800 CR850 CR10X CR1000 CR3000 CR23X CR X CR7 Cable Shield 12 V 12 V 12 V +12 V 12 V C1 C4 C1 C8 C1 C8 EXCIT 1 4 EXCITATION C1 C4 C1 C8 C1 C8 C1 C6 725 Card Control FIURE wire ¼ bride strain with multiplexer wirin 5

12 Althouh this requires a 4WFBS module for each strain ae, it is important because placin relays internal a Wheatstone bride strain system is discouraed. Any chane in resistance of the multiplexer s relay contacts would result in a correspondin chane in the bride s output voltae. Chanes in contact resistance can be induced by temperature fluctuations, oxidation, environmental conditions, and normal wear of contact surfaces. The specification for the relays that are used in our multiplexers state that initial contact resistance will be less than 100 milliohms (AM16/32B). There is not a specification for chane in contact resistance for the relays because there are so many variables that affect contact resistance. Test reports exist for various test conditions that show contact resistance chanin over time by 10 to 20 milli- Ohms. These tests were performed usin static test temperatures, so it is safe to assume that real world conditions would result in larer resistance shifts. When strain aues are used in the Wheatstone bride, small chanes in contact resistance result in lare apparent strains. To understand the error that can be introduced from allowin the relay contacts to be internal of the Wheatstone bride, let us assume that the two relays carryin the current from the strain ae vary by 20 milliohms (40 milliohm total variance or ΔR = 40 mω ). Insertin this into equation 3.3, usin a 120 ohm strain ae with a ae factor of 2 results in an apparent strain of about 167 με. 167με = 6 ( 1 10 ) 0. 04Ω 2 120Ω Quarter Bride Strain with 3 Wire Element Calculations As noted in Section 3, in real life applications the Wheatstone bride starts out unbalanced. The strain aue is never perfectly at its nominal resistance even prior to installation. The installation process can lead to even more deviation from this nominal state. In addition, lead resistance can cause an initial apparent strain readin. To remove this initial offset, a zero measurement can be made with the aue installed. This zero measurement can be incorporated into the dataloer proram and subsequent measurements can report strain relative to this zero basis point. Strain is calculated in terms of the result of the full bride measurement. This result is the measured bride output voltae divided by the bride excitation voltae V out / Vex. (The actual result of the full bride instruction is the millivolts output per volt of excitation, 1000 V out / V ex ) The result of the zero measurement, 1000 Vout 0 / Vex can be stored and used to calculate future strain measurements. The chane in the full bride measurement from the zero state, V r, is used in the calculation of the strain. Vr = ( Vout / Vex ) ( Vout 0 / Vex ) Usin V r from equation 4.1.1, the strain is calculated usin equation ε = 4Vr F( 1 2V ) r The calculations are covered in more detail in Section

13 4.1.3 Quarter Bride Strain with 3 Wire Proram Examples CRBasic Prorammin This section is broken out into CRBasic prorams and EDLO prorams. These prorams are only to be used as examples. Besides addin additional measurement instructions, the prorams will need to have the scan and data storae intervals altered for actual applications. Refer to the dataloer s manuals and/or the CRBasic Editor s help files for detailed information on the proram instructions used as well as additional proram examples. Dataloers that use CRBasic include our CR800, CR850, CR1000, CR3000, CR5000, and CR9000(X). CRBasic uses the StrainCalc Instruction for calculatin strain from the output of different full bride confiurations: StrainCalc(Dest,Reps,Source,BrZero,BrConfi,aeFactor,PoissonRatio) Source is the variable holdin the current result from the full bride measurement BrZero is the zero measurement; this parameter uses the results of a previous full bride measurement instruction when the ae is at the zero condition (multiplier=1, offset=0, mv/v) directly. BRCode for the Bride Confiuration used with the 4WFBS module should be set to -1 for a quarter bride strain circuit. Enter the actual ae factor in the aefactor parameter. Enter 0 for the Poisson ratio parameter, which is not used with ¼ Bride strain circuits. Example Proram 4.1. CR9000X ¼ bride Strain with 3 reps This example proram measures the output from the Wheatstone bride usin the BrFull instruction. The output from this instruction is input into the StrainCalc instruction in order to calculate the raw µstrain value. This proram does not use a zero offset readin. See Example Proram 4.2 for an example that performs a zero calibration. ' Proram name: STRAIN.C9X Public StrainMvperV(3) : Units StrainMvperV = mv_per_v 'Raw Strain dimensioned source Public Strain(3) : Units Strain = ustrain ustrain dimensioned source Public F(3) 'Dimensioned aue factor DataTable(STRAIN,True,-1) DataInterval(0,0,0,100) CardOut(0,-1) Sample (3,Strain(),IEEE4) Sample (3,StrainMvperV(),IEEE4) EndTable 'Trier, auto size 'Synchronous, 100 lapses, autosize 'PC card, size Auto '3 Reps, ustrain, Resolution 3Reps,Stain mvolt/volt, Resolution 'End of table STRAIN BeinPro 'Proram beins here F(1) = 2.1 : F(2) = 2.2 : F(3) = 2.3 'Initialize aue factors for Strain( ) 7

14 Scan(10,mSec,100,0) 'Scan once every 10 msecs, non-burst BrFull(StrainMvperV(),3,mV50,4,1,5,7,1,5000,True,True,70,100,1,0) StrainCalc(Strain(),3,StrainMvperV(),0,-1,F(),0) 'Strain calculation CallTable STRAIN Next Scan 'Loop up for the next scan SlowSequence Scan(1,Sec,0,0) Calibrate BiasComp Next Scan EndPro 'Slow sequence Scan to perform temperature ' compensation on DAQ 'Corrects ADC offset and ain 'Corrects ADC bias current 'Proram ends here Example Proram 4.2. CR9000X ¼ bride Strain with 3 reps and zero offset This example proram starts out with Example Proram 4.1 and adds instructions (hihlihted) to perform a zero calibration. As all strain circuits have a zero or initial imbalance that is related to the circuit rather than the member underoin strain, a zero readin is often used to offset or remove this apparent strain. Aain, see the manual and CRBasic editor s Help file for more in-depth discussion on the instructions. The FieldCalStrain instruction takes care of the underlyin math for the zeroin usin equation The LoadFieldCal instruction facilitates the reloadin of the calibration factors when the loer is powered up. In addition, the prorammer should create a DataTable (we have called this DataTable Calib in the example) to store the calibration factors each time a calibration is done. The NewFieldCal is a Boolean fla variable that is only hih durin the Scan that a calibration has been completed. It is used in the DataTable instruction s trier parameter to trier the table to record a record. The SampleFieldCal output instruction is used to inform the loer to store all of the calibration factors that are controlled usin the FieldCalStrain instruction. ' Proram name: STRAIN0.C9X Public StrainMvperV(3) : Units StrainMvperV = mv_per_v 'Raw Strain dimensioned source Public Strain(3) : Units Strain = ustrain ustrain dimensioned source Public F(3) 'Dimensioned aue factor Public ZeromV_V(3), ZeroStrain(3) Public ZReps, ZIndex, ModeVar DataTable(STRAIN,True,-1) DataInterval(0,0,0,100) CardOut(0,-1) Sample (3,Strain(),IEEE4) Sample (3,StrainMvperV(),IEEE4) EndTable DataTable (Calib,NewFieldCal,10) SampleFieldCal EndTable 'Trier, auto size 'Synchronous, 100 lapses, autosize 'PC card, size Auto '3 Reps, ustrain, Resolution 3Reps,Stain mvolt/volt, Resolution 'End of table STRAIN Table for calibration factors from zeroin User should collect these to his computer for future reference 8

15 BeinPro 'Proram beins here F(1) = 2.1 : F(2) = 2.2 : F(3) = 2.3 'Initialize aue factors for Strain( ) ZReps = 3 : ZIndex = 1 initialize cal reps and index pointer LoadFieldCal(True) Load prior calibration factors Scan(10,mSec,100,0) 'Scan once every 10 msecs, non-burst FieldCalStrain(10,StrainMvperV(),ZReps,0,ZeromV_V(),ModeVar,0,ZIndex,1,0,Strain()) BrFull(StrainMvperV(),3,mV50,4,1,5,7,1,5000,True,True,70,100,1,0) StrainCalc(Strain(),3,StrainMvperV(),ZeromV_V(),-1,F(),0) 'Strain calculation CallTable STRAIN CallTable Calib Next Scan 'Loop up for the next scan SlowSequence Scan(1,Sec,0,0) Calibrate BiasComp Next Scan EndPro 'Slow sequence Scan to perform 'temperature compensation on the DAQ 'Corrects ADC offset and ain 'Corrects ADC bias current 'Proram ends here Example Proram 4.3. CR1000 ¼ Bride Strain with 3 reps and zero offset This example proram performs the same tasks as Example Proram 4.2, only it is a CR1000 proram instead of a CR9000X proram. There are sliht differences such as rane codes and the fact that the CR1000 does not have a Slot parameter for its measurement instructions. This proram is more similar to what a CR800, CR3000, or a CR5000 proram would look like than the CR9000X proram. ' Proram name: STRAIN0.CR1 Public StrainMvperV(3) : Units StrainMvperV = mv_per_v 'Raw Strain dimensioned source Public Strain(3) : Units Strain = ustrain ustrain dimensioned source Public F(3) 'Dimensioned aue factor Public ZeromV_V(3), ZeroStrain(3) Public ZReps, ZIndex, ModeVar DataTable(STRAIN,True,-1) DataInterval(0,0,0,100) CardOut(0,-1) Sample (3,Strain(),IEEE4) Sample (3,StrainMvperV(),IEEE4) EndTable DataTable (Calib,NewFieldCal,10) SampleFieldCal EndTable 'Trier, auto size 'Synchronous, 100 lapses, autosize 'PC card, size Auto '3 Reps, ustrain, Resolution 3Reps,Stain mvolt/volt, Resolution 'End of table STRAIN Table for calibration factors from zeroin User should collect these to his computer for future reference BeinPro 'Proram beins here F(1) = 2.1 : F(2) = 2.2 : F(3) = 2.3 'Initialize aue factors for Strain( ) ZReps = 3 : ZIndex = 1 initialize cal reps and index pointer LoadFieldCal(True) Load prior calibration factors Scan(100,mSec,100,0) 'Scan once every 10 msecs, non-burst FieldCalStrain(10,StrainMvperV(),ZReps,0,ZeromV_V(),ModeVar,0,ZIndex,1,0,Strain()) BrFull(StrainMvperV(),3,mV7_5,1,1,3,2500,True,True,450,500,1,0) StrainCalc(Strain(),3,StrainMvperV(),ZeromV_V(),-1,F(),0) 'Strain calculation CallTable STRAIN CallTable Calib Next Scan 'Loop up for the next scan 9

16 Example Proram 4.3. CR1000 ¼ Bride Strain usin an AM16/32B Multiplexer with 16 reps and zero offset This example proram has 16 strain aes multiplexed throuh an AM16/32 Multiplexer and uses FieldCalStrain for zeroin. ' Proram name: QuarterStrain with Zero and Mux.CR1 ' This is only an example proram and should be used only for help in creatin a usable proram ' WIRIN ' CR1000 to AM16/32 Multiplexer Control ' C1 (Control Port 1) Res (Reset) ' C2 (Control Port 2) Clk (Clock) ' ND (round) ' 12V 12V ' CR1000 to AM16/32 Common TIMs to AM16/32 Banks ' Diff 1H to Common Even Hi Blk Wire to Bank Odd Lo ' Diff 1L to Common Even Lo TIM H to Bank Even Hi ' EX1 to Common Odd Lo Tim L to Bank Even Lo ' A to Common nd Tim A to Bank Even A '\\\\\\\\\\\\\\\\\\\\\\\DECLARE VARIABLES and CONSTANTS /////////////////////// Const REPS = 16 'Strain ae sensor count Public MVpV(REPS) : Units MVpV = mv_v 'mv per Volt output from Bride Measurement Public STRAIN(REPS) : Units STRAIN = ustrain 'Variable where us is stored, Const BATCH_F = 2.1 : Public F(REPS) 'Batch ae Factor Public mv_vzero(reps) : Units mv_vzero = mv_v 'Variable for Zero mv per V readin Public CalReps, ZeroMode, ZeroStartIdx, ZeroCalAvs 'Used by wizard for zeroin Public CalFileLoaded As Boolean Dim I '\\\\IF DESIRED (NOT REQUIRED): IVE STRAIN VARIABLES UNIQUE ALIAS NAMES //////// Alias STRAIN(1) = Strain1 : Alias STRAIN(2) = Strain2 : Alias STRAIN(3) = Strain3 Alias STRAIN(4) = Strain4 : Alias STRAIN(5) = Strain5 : Alias STRAIN(6) = Strain6 Alias STRAIN(7) = Strain7 : Alias STRAIN(8) = Strain8 : Alias STRAIN(9) = Strain9 Alias STRAIN(10) = Strain10 : Alias STRAIN(11) = Strain11 : Alias STRAIN(12) = Strain12 Alias STRAIN(13) = Strain13 : Alias STRAIN(14) = Strain14 : Alias STRAIN(15) = Strain15 Alias STRAIN(16) = Strain16 '\\\\\\\\\\\\\\\\\\\\\\\\ OUTPUT SECTION //////////////////////// ' Table STRAIN stores ustrain and raw mv per Volt measurements to the PC Card DataTable(STRAIN,True,-1) 'Trier, auto size DataInterval(0,0,0,100) 'Synchronous, 100 lapses CardOut(0,-1) 'PC card, Autosize Sample (REPS,STRAIN(),IEEE4) 'Sample ustrain Sample (Reps,mVpV(),IEEE4) 'Sample raw mv per Volt values EndTable 'End of table ' Table CalHist uses SampleFieldCal which stores all of the Calibration constants ' When a calibration function is complete, user should always collect this Table as a record DataTable(CalHist,NewFieldCal,50) SampleFieldCal EndTable '\\\\\\\\\\\\\\\\\\\\\\\\MAIN PRORAM SECTION //////////////////////// BeinPro 'Proram beins here For I = 1 To REPS ' For the 16 aes F(I) = BATCH_F 'Assin default aue factor (2.1) to F array elements Next I 'Loop back up until complete CalFileLoaded = LoadFieldCal(1) 'Load the Cal constants if proram sinature matches 10

17 Scan(1,Sec,10,0) 'Scan once a Second PortSet (1,1 ) 'Turn on AM16/32 usin C1 I = 1 Delay (0,150,mSec) 'required Delay for AM16/32 multiplexer SubScan (0,0,16) PulsePort (2,10000) 'Pulse port C2 hi and low to clock the multiplexer BrFull(MVpV(I),1,mV7_5C,1,VX1,1,2500,True,True,250,500,1,0) 'Full Bride measurement StrainCalc(Strain(I),1,MVpV(I),mV_VZero(I),-1,F(I),0) 'Strain calculation I = I + 1 'Increment I NextSubScan PortSet (1,0 ) 'Turn on AM16/32 usin C1 FieldCalStrain(10,MVpV(),CalReps,0,mV_VZero(),ZeroMode,0,ZeroStartIdx,ZeroCalAvs,0,STRAIN()) CallTable CalHist CallTable STRAIN Next Scan 'Loop up for the next scan EndPro 'Proram ends here Edlo The followin examples for the CR10(X), 21X, and CR7 all have subroutines that measures the unstrained "zero" output of the strain ae. The examples calculate strain usin equation for a strain ae with a F=2. These are just examples. Besides addin additional measurement instructions, the prorams will probably need to have the scan and data storae intervals altered for actual applications. The instructions in the subroutine will also need to be modified for the actual ae factor. Dataloers that use Edlo include CR510, CR10(X), 21X, and CR7. The Edlo instruction that is used to measure strain aes is Instruction 6 Full Bride. The Input Locations assinments used in CR10(X), 21X, and CR7 Examples are listed in Table 4-1. TABLE 4-1. Input Locations Used in CR10(X), 21X, and CR7 Examples Addr Name 1 mvperv 2 mvperv_0 3 Vr 4 ustrain 5 Count 6 F 7 _4e6 8 Mult 9 1_2Vr 10 Vr_1_2Vr 11

18 Example Proram 4.4. CR10X ¼ Bride Strain with 1 rep and zero offset ;{CR10X} *Table 1 Proram 01: 1 Execution Interval (seconds) 1: If Fla/Port (P91) ;On the first execution (Fla 1 is low) 1: 21 Do if Fla 1 is Low ;or when user sets Fla 1 low 2: 1 Call Subroutine 1 ;call the zeroin subroutine 2: Full Bride (P6) ;Measure the strain ae 1: 1 Reps 2: 22 ± 7.5 mv 60 Hz Rejection Rane 3: 1 DIFF Channel 4: 1 Excite all reps withexchan 1 5: 2500 mv Excitation 6: 1 Loc [ mvperv ] 7: 1 Mult 8: 0 Offset 3: X-Y (P35) ;Subtract zero readin from the 1: 1 X Loc [ mvperv ] ;measurement 2: 2 Y Loc [ mvperv_0 ] 3: 3 Z Loc [ Vr ] 4: X*F (P37) ;Chane Vr from mv/v to V/V 1: 3 Loc [ Vr ] 2: : 3 Loc [ Vr ] ;The followin instructions calculate microstrain 5: Z=X*F (P37) 1: 3 X Loc [ Vr ] 2: -2 F 3: 9 Z Loc [ 1_2Vr ] 6: Z=Z+1 (P32) 1: 9 Z Loc [ 1_2Vr ] 7: Z=X/Y (P38) 1: 3 X Loc [ Vr ] 2: 9 Y Loc [ 1_2Vr ] 3: 10 Loc [ Vr_1_2Vr ] 8: Z=X*Y (P36) 1: 10 X Loc [ Vr_1_2Vr ] 2: 8 Y Loc [ Mult ] 3: 4 Z Loc [ ustrain ] ; Output Section : This example outputs an averae of the 1 second readins ;once per minute. 09: If time is (P92) 1: 0 Minutes (Seconds --) into a 2: 1 Interval (same units as above) 3: 10 Set Output Fla Hih 10: Set Active Storae Area (P80) 1: 1 Final Storae Area 1 2: 1 Array ID ;Set Array ID = 1 for measurement data 11: Real Time (P77) 1: 1110 Year,Day,Hour/Minute 12

19 12: Averae (P71) 1: 1 Reps 2: 4 Loc [ ustrain ] *Table 2 Proram 2: Execution Interval (seconds) *Table 3 Subroutines 1: Beinnin of Subroutine (P85) ;Subroutine to measure "zero" 1: 1 Subroutine 1 2: Do (P86) ;This prevents callin subroutine 1: 11 Set Fla 1 Hih ;until user sets fla 1 low aain. 3: Z=F (P30) ;Set counter use for averae to 0 1: 0 F 2: 0 Exponent of 10 3: 5 Z Loc [ Count ] 4: Z=F (P30) ;load 4 million (4*uS/S) into input location 1: 4 F 2: 6 Exponent of 10 3: 7 Z Loc [ _4e6 ] 5: Z=F (P30) ;Load ae Factor into input location 1: 2 F ;Enter the actual ae Factor here 2: 0 Exponent of 10 3: 6 Z Loc [ F ] 6: Z=X/Y (P38) ;calculate multiplier to use with strain 1: 7 X Loc [ _4e6 ] ;calculation 2: 6 Y Loc [ F ] 3: 8 Z Loc [ Mult ] 7: Beinnin of Loop (P87) ;Loop throuh 5 times to obtain averae 1: 0 Delay ;zero readin 2: 5 Loop Count 8: Z=Z+1 (P32) ;Increment Counter used to determine 1: 5 Z Loc [ Count ] ;when to output 9: Full Bride (P6) ;Measure Strain ae 1: 1 Reps 2: 22 ± 7.5 mv 60 Hz Rejection Rane 3: 1 DIFF Channel 4: 1 Excite all reps withexchan 1 5: 2500 mv Excitation 6: 1 Loc [ mvperv ] 7: 1 Mult 8: 0 Offset 10: IF (X<=>F) (P89) ;Check for last pass throuh loop 1: 5 X Loc [ Count ] ;to set output fla 2: 3 >= 3: 5 F 4: 10 Set Output Fla Hih 11: Set Active Storae Area (P80) ;Direct averaed "zero" readin 1: 3 Input Storae Area ;to input storae 2: 2 Array ID or Loc [ mvperv_0 ] 13

20 12: Averae (P71) 1: 1 Reps 2: 1 Loc [ mvperv ] 13: If Fla/Port (P91) ;When averae is calculated, 1: 10 Do if Output Fla is Hih (Fla 0) ;also send it to Final Storae 2: 10 Set Output Fla Hih 14: Set Active Storae Area (P80) ;Direct Output to Final Storae 1: 1 Final Storae Area 1 2: 11 Array ID ;set Array ID = 11 for zero data 15: Real Time (P77) 1: 110 Day,Hour/Minute 16: Sample (P70) 1: 1 Reps 2: 2 Loc [ mvperv_0 ] 17: End (P95) 18: End (P95) End Proram Example Proram X ¼ Bride Strain with 1 rep and zero offset ;{21X} *Table 1 Proram 01: 1 Execution Interval (seconds) ;Other measurements could be inserted here or before the Output section 1: If Fla/Port (P91) ;On the first execution (Fla 1 is low) 1: 21 Do if Fla 1 is Low ;or when user sets Fla 1 low 2: 1 Call Subroutine 1 ;call the zeroin subroutine 2: Full Bride (P6) ;Measure the strain ae 1: 1 Reps 2: 2 ± 15 mv Slow Rane 3: 1 DIFF Channel 4: 1 Excite all reps withexchan 1 5: 5000 mv Excitation 6: 1 Loc [ mvperv ] 7: 1 Mult 8: 0 Offset 3: Z=X-Y (P35) ;Subtract zero readin from the 1: 1 X Loc [ mvperv ] ;measurement 2: 2 Y Loc [ mvperv_0 ] 3: 3 Z Loc [ Vr ] 4: Z=X*F (P37) ;Chane Vr from mv/v to V/V 1: 3 X Loc [ Vr ] 2: F 3: 3 Z Loc [ Vr ] 14

21 ;The followin instructions calculate microstrain 5: Z=X*F (P37) 1: 3 X Loc [ Vr ] 2: -2 F 3: 9 Z Loc [ 1_2Vr ] 6: Z=Z+1 (P32) 1: 9 Z Loc [ 1_2Vr ] 7: Z=X/Y (P38) 1: 3 X Loc [ Vr ] 2: 9 Y Loc [ 1_2Vr ] 3: 10 Z Loc [ Vr_1_2Vr ] 8: Z=X*Y (P36) 1: 10 X Loc [ Vr_1_2Vr ] 2: 8 Y Loc [ Mult ] 3: 4 Z Loc [ ustrain ] ;Output Section ;This example outputs an averae of the 1 second readins ;once per minute. 9: If time is (P92) 1: 0 Minutes (Seconds --) into a 2: 1 Interval (same units as above) 3: 10 Set Output Fla Hih 10: Set Active Storae Area (P80) 1: 1 Final Storae Area 1 2: 1 Array ID ;Set Array ID = 1 for measurement data 11: Real Time (P77) 1: 1110 Year,Day,Hour/Minute 12: Averae (P71) 1: 1 Reps 2: 4 Loc [ ustrain ] *Table 2 Proram 01: Execution Interval (seconds) *Table 3 Subroutines 1: Beinnin of Subroutine (P85) ;Subroutine to measure "zero" 1: 1 Subroutine 1 2: Do (P86) ;This prevents callin subroutine 1: 11 Set Fla 1 Hih ;until user sets fla 1 low aain. 3: Z=F (P30) ;Set counter use for averae to 0 1: 0 F 2: 5 Z Loc [ count ] 4: Z=F (P30) ;load 4000 into 1: 4000 F ;input location 2: 7 Z Loc [ 4e6 ] 5: Z=X*F (P37) ;Multiply by 1000 to et (4*uS/S) 1: 7 X Loc [ 4e6 ] 2: 1000 F 3: 7 Z Loc [ 4e6 ] 15

22 6: Z=F (P30) ;Load ae Factor into input location 1: 2 F ;Enter the actual ae Factor here 2: 6 Z Loc [ F ] 7: Z=X/Y (P38) ;calculate multiplier to use with strain 1: 7 X Loc [ 4e6 ] ;calculation 2: 6 Y Loc [ F ] 3: 8 Z Loc [ Mult ] 8: Beinnin of Loop (P87) ;Loop throuh 5 times to obtain averae 1: 0 Delay ;zero readin 2: 5 Loop Count 9: Z=Z+1 (P32) ;Increment Counter used to determine 1: 5 Z Loc [ count ] ;when to output 10: Full Bride (P6) ;Measure Strain ae 1: 1 Reps 2: 2 ± 15 mv Slow Rane 3: 1 DIFF Channel 4: 1 Excite all reps withexchan 1 5: 5000 mv Excitation 6: 1 Loc [ mvperv ] 7: 1 Mult 8: 0 Offset 11: IF (X<=>F) (P89) ;Check for last pass throuh loop 1: 5 X Loc [ count ] ;to set output fla 2: 3 >= 3: 5 F 4: 10 Set Output Fla Hih 12: Set Active Storae Area (P80) ;Direct averaed "zero" readin 1: 3 Input Storae ;to input storae 2: 2 Array ID or Loc [ mvperv_0 ] 13: Averae (P71) 1: 1 Reps 2: 1 Loc [ mvperv ] 14: If Fla/Port (P91) ;When averae is calculated, 1: 10 Do if Output Fla is Hih (Fla 0) ;also send it to Final Storae 2: 10 Set Output Fla Hih 15: Set Active Storae Area (P80) ;Direct Output to Final Storae 1: 1 Final Storae 2: 11 Array ID ;set Array ID = 11 for zero data 16: Real Time (P77) 1: 110 Day,Hour/Minute 17: Sample (P70) 1: 1 Reps 2: 2 Loc [ mvperv_0 ] 18: End (P95) 19: End (P95) End Proram 16

23 4.2 Quarter Bride Strain with 2 Wire Element NOTE Althouh a two wire ae can be used with the 4WFBS TIM, due to the issues outlined in Section 4.4.3, it is not recommended. An exception may be applications with short leads in a stable temperature environment. A 2-wire quarter bride strain circuit is shown in fiure R 2 =1KΩ R D Excite V - + R 4 =aue R 1 =1KΩ FIURE Two wire quarter bride strain circuit In this circuit, R1 and R2 are 1000 ohm resistors makin up the back plane of the Wheatstone bride, as is done in the TIM desin. R D is the complementary resistor, or Dummy Resistor, that has a nominal resistance of the un-strained ae. The 4 th resistive element is the active strain ae. Strain aes are available in nominal resistances of 120, 350, and 1000 ohms. The 4WFBS model must match the nominal resistance of the ae (e.., the 4WFBS120 is used with a 120 ohm strain ae). As can be seen in Fiure 4.2-1, both sensor leads are in the same arm of the Wheatstone bride. Not only does this affect the sensitivity of the ae, the output from this circuit will include temperature induced line resistance errors. See Section 4.4.3, Lead Compensation usin ¼ Bride Strain with 2 Wire Element for more information on issues with usin 2 wire aes Quarter Bride Strain with 2 Wire Element Wirin To use a two wire element strain aue with the 4WFBS TIM requires a jumper wire be placed between the H and L terminal of the TIM module as shown in Fiure

24 Dataloer Vx H H Jumper Wire L R 2 R D L or A R 1 aue or Shield FIURE Wirin for 2-wire aues Two Wire ¼ Bride use with Multiplexers and Equations The equations to resolve the strain, prorammin of the loer, and methods of usin with multiplexers are the same as those covered in Section 4.1 for the 3- Wire Strain aue. The only variance is the wirin of the ae to the TIM. 4.3 Quarter Bride Strain with Dummy ae An undesirable property of strain aues is that of resistance chane with chanes in temperature. This is true even for the self-temperature compensatin strain aes on the market today. Supplied with each packae of strain aes are raphs and equations for the variance in the output of the strain ae due to thermal chanes (referred to as thermal output or apparent strain) and for the variation of the ae factor with temperature. These raphs are based on the assumption that the aes are mounted on a material with the iven thermal coefficient of expansion (TCE). The TCE value is included in the ae type nomenclature. Followin are some typical equations supplied. Equation is used to calculate the thermal output variance (µε TO ) with the result in μstrain. Equation is used to determine the chane in the aue factor (F) due to temperature chanes. Both are based on temperature in derees Celsius (T). με TO = T 0.05T E T 3.93E T adj raw ( T ) Fraw 4 F = F E As an example, let us assume we use a aue with a F of 2.00 in a test that started at 24 C and 0 μstrain, and ended at 50 C and a recorded strain value of 1000 μstrain. The thermal output strain, µε TO, at 50 C would be μstrain. The error in the ae factor would be 0.364% with a resultant F adj of The corrected strain would be 967 μstrain: ( 1000με 29.3με ) / με cor = The uncorrected value had an error of approximately 3.3%. And if the endin strain would have been 100 μstrain instead of 1000 μstrain, the error would have been around 30%. 18

25 Another temperature induced error in a quarter bride strain circuit is due to the Temperature Coefficient of Resistance (TCR) of the completion resistor in the arm opposite the strain aue. The 4WFBS TIMs use a hih quality resistor havin a TCR of 0.8ppm/ C to minimize these errors. For our example above, this could lead to an error in the readin of approximately 10 μstrain, assumin that the dataloer experiences the same level of temperature variation. This error could be additive or subtractive to the other errors as the resistor manufacturer does not specify the polarity of the chane in resistance, only the absolute manitude. These errors, with exception to the completion resistor s TCR, can be mathematically compensated for to some deree. It should be remembered that the curves and equations iven are the averae for the iven batch of aes and are only applicable when mountin on the specified material. An alternative approach to eliminate the errors is to either use a dummy ae, from the same batch mounted on identical material, or to use a half or full bride strain circuit. Dummy aues can be used to compensate for these false apparent strain readins. A strain aue that is mounted on a coupon that is not underoin mechanical stress and is used as the resistive element for the Wheatstone bride arm opposite the active ae is referred to as a Dummy aue. This non-active aue in the other arm of the Wheatstone bride is referred to as a dummy aue because it is not subjected to load induced strains. With the two opposin aues experiencin the same temperature conditions, the temperature effects on the active ae will be nullified by the equivalent temperature effects on the dummy aue. Fiure depicts a Quarter Bride Strain circuit with a Dummy aue. R 2 =1 KΩ L 3 3 Dummy aue - + L 2 R 1=1 KΩ L 1 Active aue FIURE Quarter bride strain circuit with dummy aue It should be noted that the coupon on which the dummy aue is mounted can still be subjected to temperature induced strains. This can be used to null temperature induced strains in the monitored member if the dummy aue is mounted to a coupon made up of material havin the same Temperature Coefficient of Resistance (TCR) as the member that the active aue is mounted to. Conversely, the dummy ae could be mounted to a coupon with a neliible TCR allowin for the monitorin of temperature induced stresses. 19

26 The 4WFBS modules can support quarter bride strain circuits usin either the completion resistor built into the TIM, or a user supplied dummy strain aue, for the Wheatstone Bride arm's resistive element opposite of the active strain aue in the bride. Wirin circuits usin a dummy ae are covered in Section Quarter Bride Strain with Dummy aue Wirin Setup Fiure illustrates the wirin of the strain ae with a dummy ae to the 4WFBS module, as well as the wirin of the module to the dataloer. This shows the dummy aue out at the remote site alon with the active ae. This is the best setup to achieve the best compensation for the apparent strain and aue factor variance due to temperature fluctuations, as it will be easier to keep the temperature of the two aes equivalent. FIURE ¼ bride strain with remote dummy aue Fiure illustrates the wirin of the strain ae to the 4WFBS module with the Dummy aue at the loer location. Apparent strain errors could result because of temperature variances between the two aues with this setup. This circuit is still utilized in some applications for ease of Shunt calibration (can shunt across Dummy ae at loer location rather than at the remote aue location). Also an existin, standard 3-wire ¼ Bride strain circuit can easily be transformed into this circuit. If lare temperature variances will exist between the active ae and the dummy ae located at the dataloer, usin the 4WFBS completion resistor can result in lower temperature induced errors. FIURE ¼ bride strain with dummy aue at dataloer 20

27 With either circuit, one lead le, L 1 or L 3, is in one of the two opposin arms of the Wheatstone bride. It is important that the ae be wired such, and that these two leads be the same lenth, diameter and wire type. It is preferable to use a twisted pair for these two wires so that they will undero the same temperature and electromanetic field variations. With this confiuration, chanes in wire resistance due to temperature occur equally in both arms of the bride with neliible effect on the output from the bride Quarter Bride Strain with Dummy aue Calculations The calculations for this bride setup are the same as for the 3-Wire Quarter Bride circuit. See Section Quarter Bride Strain with3 Wire Element Calculations for details Quarter Bride Strain with Dummy aue Example Prorams The prorammin for this bride setup is the same as for the 3-Wire Quarter Bride circuit. See Section Quarter Bride Strain with3 Wire Proram Examples for details. 4.4 Quarter Bride Strain Lead Resistance Compensation When usin quarter bride strain (full bride with one active element) with lon lead lenths, errors can be introduced due to the resistance of the leads. This section covers both mathematical and Shunt Calibration methods used to rectify these errors. The techniques covered in the section can be used with circuits usin a 4WFBS s completion resistor or a dummy aue for the resistive element in the third arm of the Wheatstone Bride (arm opposite of active aue). The only difference is that when usin a dummy aue, the 4WFBS module s old shunt receptacles cannot be used. These receptacles are connected to the dummy resistor supplied by the 4WFBS module. One potential error with lon leads is due to the leads' resistance chane from temperature fluctuations. When usin a three wire strain aue, wired as depicted in Fiure Wire ¼ Bride Strain Wirin, with the three leads all the same lenth and laid out toether (all three experience the same temperature swins), the leads' resistance chanes are self compensatin. It is preferable to use a twisted pair for the two wires (L and ) carryin the current so that they definitely undero the same temperature and electromanetic field variations. With this confiuration, chanes in wire resistance due to temperature occur equally in both arms of the bride with neliible effect on the output from the bride. Another error that is introduced when usin lon leads, is a sensitivity reduction of the system. There are two methods to rectify this error. The first is mathematical. The second is to perform a shunt calibration. Sections and cover these methods for ¼ Bride Strain circuits Mathematical Lead Compensation for 3-Wire, ¼ Bride Strain The same equations pertain whether a completion (dummy) resistor or a dummy aue is used to complete the third arm of the Wheatstone Bride. So the material in this section is relevant for wirin setups shown in Fiures 4.1-2, 4.3-2, and The math and the prorams used would be identical for all three of these circuits. 21

28 Mathematical Lead Compensation Circuit and Equations If the lead resistance is known, the sensitivity error can be mathematically corrected for by multiplyin the output by a simple factor (1+R L /R ) where R L is the nominal resistance of one of the lead les and R is the resistance of the strain aue. The aue Factor can be multiplied by the inverse of this value, R /(R + R L ), to derive an adjusted aue Factor. F adj = F raw R R + R L The adjusted aue Factor, F adj, would be used in the StrainCalc function to derive the µstrain. The proof used to derive this adjusted aue Factor is shown below: R 2 = 1KΩ R D Excite - + R L R 4 =aue R 1 = 1KΩ R L R L FIURE Three wire ¼ bride strain circuit Balanced Bride Condition E E O I BAL = R R + R L + R + R L D + R L R1 R + R Strained Bride Condition E E O I STR = R R + R + ΔR L + R + R + R + ΔR L D L R1 R + R Chane in Bride Output (V R ) V R E = E O I STR E E O I BAL = R + R + ΔR L R + 2R + R + ΔR D L R D R + R L + R + 2R L

29 Assume R D = R V R R + R + ΔR L = 2R + 2R + ΔR L R 2R + RL + 2R L Simplify V = R ( 2R + 2R + ΔR )( 2R + 2R ) R ΔR L + R ΔR L L Solve for ΔR /R ΔR R = 4V R R + R ( 1-2V ) R R L ΔR 10 Use the aue Factor to calculate micro-strain με = R F 4V με = F R 10 6 ( 1-2V ) R R + R R L Mathematical Lead Compensation Prorams Example Proram 4.6. CR9000X ¼ Bride Strain with zero offset and Lead Compensation This proram starts with Example Proram 4.2 and adds instructions to mathematically compensate for the leads resistances effects on the aue Factor (sensitivity effect). Added instructions are hihlihted. ' Proram name: StrainSH.C9X Public StrainMvperV(3) : Units StrainMvperV = mv_per_v 'Raw Strain dimensioned source Public Strain(3) : Units Strain = ustrain ustrain dimensioned source Dim F(3) 'Dimensioned aue factor Public ZeromV_V(3), ZeroStrain(3) Public ZReps, ZIndex, ModeVar Public Leadlenth(3), Lead_R(3),F_Adjusted(3), Public I, LeadRper100ft, aue_r DataTable(STRAIN,True,-1) DataInterval(0,0,0,100) CardOut(0,-1) Sample (3,Strain(),IEEE4) Sample (3,StrainMvperV(),IEEE4) EndTable DataTable (Calib,NewFieldCal,10) SampleFieldCal EndTable 'Trier, auto size 'Synchronous, 100 lapses, autosize 'PC card, size Auto '3 Reps, ustrain, Resolution 3Reps,Stain mvolt/volt, Resolution 'End of table STRAIN Table for calibration factors from zeroin User should collect these to his computer for future reference 23

30 BeinPro 'Proram beins here F(1) = 2.1 : F(2) = 2.2 : F(3) = 2.3 'Initialize aue factors for Strain( ) LeadLenth(1) = 1.25 ' load lead lenths (100s of feet) LeadLenth(2) = 1.50 LeadLenth(3) = 2.00 LeadRper100ft = 2.5 '24 aue copper wire lead R is ohms/ft aue_r = 350 ' Load Strain aue Resistance For I = 1 To 3 ' Loop throuh calculate the adjusted aue factors Lead_R(I) = LeadLenth(I) * LeadRper100ft F_Adjusted(I) = F(I) * (aue_r/(aue_r + Lead_R(I))) Next I ZReps = 3 : ZIndex = 1 initialize cal reps and index pointer LoadFieldCal(True) Load prior calibration factors Scan(10,mSec,100,0) 'Scan once every 10 msecs, non-burst FieldCalStrain(10,StrainMvperV(),ZReps,0,ZeromV_V(),ModeVar,0,ZIndex,1,0,Strain()) BrFull(StrainMvperV(),3,mV50,4,1,5,7,1,5000,True,True,70,100,1,0) StrainCalc(Strain(),3,StrainMvperV(),ZeromV_V(),-1,F(),0) 'Strain calculation CallTable STRAIN CallTable Calib Next Scan 'Loop up for the next scan SlowSequence Scan(1,Sec,0,0) Calibrate BiasComp Next Scan EndPro 'Slow sequence Scan to perform temperature ' compensation on DAQ 'Corrects ADC offset and ain 'Corrects ADC bias current 'Proram ends here 24

31 Example Proram 4.7. CR10X ¼ Bride Strain with 16 reps, usin multiplexer with zero offset and Lead Compensation Calculations usin Lead resistance Input Locations Used in CR10(X)Proram Example X.X Addr Name Addr Name Addr Name Addr Name 1 mvperv01 36 AdjF01 70 LeadFt F01 2 mvperv02 37 AdjF02 71 LeadFt F02 3 mvperv03 38 AdjF03 72 LeadFt F03 4 mvperv04 39 AdjF04 73 LeadFt F04 5 mvperv05 40 AdjF05 74 LeadFt F05 6 mvperv06 41 AdjF06 75 LeadFt F06 7 mvperv07 42 AdjF07 76 LeadFt F07 8 mvperv08 43 AdjF08 77 LeadFt F08 9 mvperv09 44 AdjF09 78 LeadFt F09 10 mvperv10 45 AdjF10 79 LeadFt F10 11 mvperv11 46 AdjF11 80 LeadFt F11 12 mvperv12 47 AdjF12 81 LeadFt F12 13 mvperv13 48 AdjF13 82 LeadFt F13 14 mvperv14 49 AdjF14 83 LeadFt F14 15 mvperv15 50 AdjF15 84 LeadFt F15 16 mvperv16 51 AdjF16 85 LeadFt F16 17 mvpervz01 52 ustrain01 86 OhmLead Ohms 18 mvpervz02 53 ustrain02 87 OhmLead Ohms 19 mvpervz03 54 ustrain03 88 OhmLead Ohms 20 mvpervz04 55 ustrain04 89 OhmLead Ohms 21 mvpervz05 56 ustrain05 90 OhmLead Ohms 22 mvpervz06 57 ustrain06 91 OhmLead Ohms 23 mvpervz07 58 ustrain07 92 OhmLead Ohms 24 mvpervz08 59 ustrain08 93 OhmLead Ohms 25 mvpervz09 60 ustrain09 94 OhmLead Ohms 26 mvpervz10 61 ustrain10 95 OhmLead Ohms 27 mvpervz11 62 ustrain11 96 OhmLead Ohms 28 mvpervz12 63 ustrain12 97 OhmLead Ohms 29 mvpervz13 64 ustrain13 98 OhmLead Ohms 30 mvpervz14 65 ustrain14 99 OhmLead Ohms 31 mvpervz15 66 ustrain OhmLead Ohms 32 mvpervz16 67 ustrain OhmLead Ohms 33 VR_1 68 Number4e3 134 AndLOhms 34 One_2Vr 69 LeadOhms 135 AdjFactor 35 Vr_1_2Vr

32 ;{CR10X} ;16SMux.CSI ;This proram calculates the strain for 16 quarter strain brides usin4 wire bride completion modules. ; It takes into account the sensitivity chanes due to lead lenth resistance. ;(1) Sensors: ; 16 strain aues multiplexed throuh an AM416 ;(2) DataInfo: ; Strain aues will be measured every 5 seconds. ; Only measurement at top of minute will be stored. ;(3) SubroutineDescrptions: ; Subroutine01: Measures the zero offset strain readin, sets the aue factor. ; Subroutine02: Outputs processed values to FinalStorae ;(4) Wirin: ; (a) Mux01: ; 10x_12V To AM416_12V 10x_ND To AM416_ND ; 10x_C3 To AM416_ResetEnable 10x_C4 To AM416_Clock ; 10x_H4 To AM416_ComH1 10x_L4 To AM416_ComL1 ; 10x_E2 To AM416_ComH2 10x_A To AM416_ComL2 ; First bank example: ; S+ To H1 S- To L1 ; SExcite To H2 Snd To L2 *Table 1 Proram 01: 5 Execution Interval (seconds) ;Loop throuh the strain aes usin the AM416: 1: Do (P86) 1: 43 Set Port 3 Hih ; Reset and Enable the AM416. 2: Beinnin of Loop (P87) 1: 0 Delay 2: 16 Loop Count 3: Do (P86) 1: 74 Pulse Port 4 ; Clock forward to the next bank on the AM416. 4: Excitation with Delay (P22) ; Delay to allow relay connection to settle. 1: 2 Ex Channel 2: 0 Delay WITHEx (units = 0.01 sec) 3: 5 Delay After Ex (units = 0.01 sec) 4: 0 mv Excitation 5: Full Bride (P6) 1: 1 Reps 2: mv Slow Rane 3: 4 DIFF Channel 4: 2 Excite all reps withexchan 2 5: 2500 mv Excitation 6: 1 -- Loc [ mvperv01 ] 7: 1.0 Mult 8: 0.0 Offset 6: End (P95) 7: Do (86) 1: 53 Set Port 3 Low ; Deactivate the AM416. ;.. 8: If Fla/Port (P91) ; If first time throuh then call zero routine. 1: 21 Do if Fla 1 is Low 2: 1 Call Subroutine 1 9: Beinnin of Loop (P87) ; This Loop calculates ustrain values: 1: 0 Delay 2: 16 Loop Count 10: Step Loop Index (P90) 1: 1 Step 26