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ERROR DEFINITIONS AND EXAMPLES 

Linearity: 

 

Linearity error is the deviation of the output from a straight line.  

Many transducers for measuring physical phenomena have outputs 
that do not vary linearly with the phenomena being measured.  
Sometimes the deviation from linear is slight and is accepted as part of 
the error of the device, in other cases manufacturers attempt to 
"linearize" the output.  Usually when this done through an analog 
means, there will be a residual non-linearity, i.e., the non-linearity is 
not completely removed.  The following non-linearity graph illustrates 
why a two point calibration (zero and full scale) is many times 
insufficient and ensures that the maximum error is achieved.  A best-fit 
straight line decreases the maximum error by ensuring that the errors 
fall evenly on both sides. 

Example of Linearity Error

-20

0

20

40

60

80

100

0

20

40

60

80

100

Input

Non-linear Output

Ideal Output

Best Fit

 

 

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53 

 

Summary of Contents for Accububble 56-0131-50-1

Page 1: ...bler System Model 5600 0131 1 Models 5600 0131 3 4 5 Models 56 0131 50 1 2 OPERATIONS MAINTENANCE MANUAL Part No 8800 1102 Revision H Sutron Corporation 21300 Ridgetop Circle Sterling Virginia 20166 T...

Page 2: ......

Page 3: ...g the Units 17 Setting User Units 17 Field Calibration 18 Configuring the Quadrature Output 5600 0131 3 and 56 0131 50 1 models only 19 Setting the Quadrature Scale Factor Threshold and Step Rate 19 S...

Page 4: ...E UNITS 52 ERROR DEFINITIONS AND EXAMPLES 53 Appendix B SDI 12 with the Sutron 8200 8200A and 8210 55 Entering Extended Commands for Configuration Purposes 55 From the Front Panel 55 From a PC connect...

Page 5: ...0131 high accuracy 0 0044 psi for pressures less than 4 4 psi 0 1 of reading for pressures 4 4 to 22 psi 0 01 ft up to 10 ft of water 0 1 of reading 10 to 50 feet of water 5600 0131 excellent stabili...

Page 6: ...lear the line of any water and refuge after initial orifice line installation or after the orifice line has been open at the AccuBubble 3 With the orifice line in water enter the command 0XPC the is n...

Page 7: ...er than 0 01 ft then either the water level changed or there is a leak in the tubing or fittings For a bubbler any bubbler to work correctly the system needs to be leak free If the system has a leak i...

Page 8: ...wire SDI 12 Circular Connector The following table contains pin descriptions for the circular connector Description Circular connector Notes SDI Data A SDI 12 Data line Battery B 8 to 28VDC Ground C N...

Page 9: ...pressure sensor power be in common with the device reading the sensor If the sensor is being read by an SDI 12 data recorder then the sensor power would come from the SDI 12 data recorder SDI 12 defin...

Page 10: ...ep size and rate The XQC command can be used to synchronize the output with the quadrature recording device The XOM command specifies whether the Quadrature output should be updated independently of S...

Page 11: ...dress If you are using the ACCUBUBBLE connected with other SDI 12 devices you will need to change the ACCUBUBBLE address Otherwise skip this section The address simply lets multiple devices share the...

Page 12: ...D9A9 Beginning with version 1 9 the ACCUBUBBLE also supports an alternate version of the set Address command as specified in SDI 12 standard version 1 2 0An where 0 is the current address of the devic...

Page 13: ...to all SDI 12 commands it supports If the ACCUBUBBLE receives a command it does not support no reply is made The reply will have one of two forms a0000 where a is the address and the 0000 indicates t...

Page 14: ...2 data recorders support the non concurrent measurement M command With the M command the data recorder collects data from the sensors one at a time Multiple long measurement time sensors When collecti...

Page 15: ...water 1 units are psi 2 units are kilopascals 3 units are cm of water 4 units are m of water 5 units are mm of water 9 units depend on user entered scale and offset If the field calibration offset is...

Page 16: ...s complete the sensor does NOT issue a service request Note this is different from the M command To request the data after a measurement aD0 where a is the address character and D0 is the command to r...

Page 17: ...ent Measurement with CRC 16 MC command The command to tell the AccuBubble to make a non concurrent measurement with a CRC 16 check on the data is aMC where a is the address character and MC is the com...

Page 18: ...t 15 units are mm of water with non zero field calibration offset 19 user units with non zero field calibration offset psi field calibration offset user scale user offset set by XE or XS set by XUU se...

Page 19: ...the values of u 0 units are feet of water 1 units are psi 2 units are kilopascals 3 units are cm of water 4 units are meters of water 5 units are mm of water 9 units depend on user entered scale and...

Page 20: ...t This returns two values the temperature and the units The units will be 0 for Celsius and 1 for Fahrenheit aM3 aC3 aMC3 aCC3 measure user scale user offset field calibration offset Use this if you w...

Page 21: ...er 2 in the example is optional If omitted the resolution is not changed Setting User Units If you want the sensor to read out in units other than feet of water psi kPa or cm of water you will need to...

Page 22: ...only if you vent the sensor to the atmosphere or have a stable known pressure on the sensor The command has the format aXS Or aXSdu use this form only when the sensor is vented to the atmosphere use...

Page 23: ...the threshold were set to zero then for every 0 001 foot of change detected by the AccuBubble the stepper would be stepped This would cause excessive power consumption on the stepper side because it...

Page 24: ...ill drive the quadrature output to update the quadrature input device NOTE If the XQS command needs to be given M5 command returns current value of Scale Threshold Rate and Operating Mode parameters i...

Page 25: ...he following formulas would be used to determine z and f z P V P P V V 1 1 2 1 2 1 f P V P P V V 1 5 1 2 1 2 1 For example suppose we want the ACCUBUBBLE to output 2V at 20 ft of water and 4V at 40 ft...

Page 26: ...3 or 56 0131 50 1 unit to update the quadrature output without an SDI 12 measurement being invoked the operating mode of the unit must be set to 88 To configure a 5600 0131 4 or 56 0131 50 2 unit to...

Page 27: ...ings this formula would reduce to on_time 0 3 0 1 per 100 ft of orifice line For sites not capable of supplying at least 12V to the pump the times may need to be increased or accept that when the batt...

Page 28: ...veraging to 10 samples at the slow speed for a sensor at address 0 There are two speed regions slow and fast If speed is 0 or omitted then the AccuBubble operates in the default more accurate slow mod...

Page 29: ...ddress will be the dip switch address C Request Default Concurrent Pressure Measurement aC aD0 attt02 ttt is the time in seconds until the measurement is ready 2 is the number of values that can be co...

Page 30: ...s the offset calibration psi C5 Request Quadrature scale factor threshold step rate and operating mode for the unit aC5 aD0 a00004 000 is the time in seconds until the measurement is ready and 04 is t...

Page 31: ...r aCC1 aD0 attt01 ttt is the time in seconds until the measurement is ready 1 is the number of values that can be collected apC where p is the signed pressure value in psi and C is the 3 character CRC...

Page 32: ...uadrature threshold r is the quadrature step rate in steps per second and m is the operating mode of the analog and quadrature outputs and C is the CRC CC6 Request Concurrent Temperature and Pressure...

Page 33: ...ither a measurement command was not issued the command was aborted by sending a new command before the measurement time expired or a service request was received I Send Identification aI a13 SUTRON 01...

Page 34: ...s that can be collected a service request atu where t is the temperature and u is the units 0 Celsius and 1 Fahrenheit Use the XUT command to set the units M3 Request User Scale User Offset and Field...

Page 35: ...r aM6 aD0 attt4 ttt is the time in seconds until the measurement is ready and 4 is the number of values that can be collected a service request atupv where t is the temperature u is the temperature un...

Page 36: ...values that can be collected a service request apC where p is the signed pressure value in psi and C is the 3 character CRC MC2 Request Temperature Measurement with CRC 16 Version 2 0 and higher aMC2...

Page 37: ...operating mode of the analog and quadrature outputs and C is 3 character CRC MC6 Request Temperature and Pressure Measurement with CRC 16 Version 2 0 and higher aMC6 aD0 attt04 ttt is the time in seco...

Page 38: ...returns its address because it does not support continuous measurements V Initiate Verify sequence aV aD0 attt5 indicating that the command will be complete in ttt seconds and 5 values can be collecte...

Page 39: ...tion offset aXExu where x is the pressure offset u indicates the units of the offset 0 feet water 1 psi Example 0XE 0 05 0 set offset to 0 05 feet a0011 indicating that the command will take 1 second...

Page 40: ...easurement is requested Only relevant for a 5600 0131 3 or 56 0131 50 1unit 80 Bubbler with Analog output SDI 12 measurements not required for the analog output to be updated 88 Bubbler with quadratur...

Page 41: ...Service request acs Where c is the number of samples to be averaged and s indicates the speed where 0 is slow and 1 is fast XPC Suggests bubbler pump and read times aXPC minpurge If a value for minpur...

Page 42: ...he level of accuracy you are looking for Ideally it should be less than 0 01 feet of water If the number is larger than what is acceptable and it is thought that the system is leak free try increasing...

Page 43: ...purge p is pump time between readings o is pump off time before readings c maximum output update cycle time XS Self Cal the Field Calibration Offset aXS or aXSdu where d and u are optional When omitt...

Page 44: ...ake sure you use XUU command to set the scale and offset for the desired user units a0012 indicating the command will be complete in 1 second and 2 values can be collected Note a D0 command issued aft...

Page 45: ...the value currently indicated by the quadrature input device All input values are standard SDI 12 values with polarity sign a0011 indicating that the command will take one 1 second to complete and tha...

Page 46: ...mand will take one 1 second to complete and that one 1 value can be collected NOTE A D0 command issued after the XAO command will return the D A value corresponding to the requested voltage The unit s...

Page 47: ...for leaks and check the 0XPT timing parameters See chapter 2 for an in depth explanation of these steps Leak Checking The System It is important to check for leaks when installing the sensor To check...

Page 48: ...about the same as the 30 second result then the change is most likely due to the actual fluctuations of the water s surface waves and ripples 44...

Page 49: ...ber for this calibration service is 8700 0005 Metrology Lab Calibration The ACCUBUBBLE does have the provision for a calibration to be performed by a Metrology Lab The calibration coefficients that ca...

Page 50: ...ntered by the XC command calibration scale is entered by the XC command field offset is entered by the XE or XS commands units scale and units offset are set by the combination of the XUP and XUU comm...

Page 51: ...nd look at the units field Verify that the desired units are selected High unstable readings when bubbler is utilized Unit has not been configured for use at the site Use the XPC and XPT commands as d...

Page 52: ...etting the field calibration offset Maintenance should be performed at least every 6 months in order to insure that the sensor meets the accuracy specifications The offset can be checked by venting th...

Page 53: ...utlet 3 8 Tube fitting Environmental Temperature 25 C to 60 C Humidity 0 95 Non condensing 56 0131 50 ACCUBUBBLE Electrical Power Required 8 16VDC Current Use 25ma 24hrs avg purging every reading Abov...

Page 54: ...d a 5600 0131 1 Not used for the 3 or 4 or 5 6411 1300 1 SDI 12 cable for use with 8200 and a 5600 0131 1 Not used for the 3 or 4 or 5 2911 1183 Black polyethylene tubing 3 8 O D X 1 8 I D 2911 1184 R...

Page 55: ...TIAL PSID Pressure is measured with respect to a second pressure port GAUGE PSIG Pressure is measured with respect to atmospheric pressure Same as a differential pressure sensor with the second port o...

Page 56: ...n based on density at 10 C PRESSURE EQUIVALENTS PSI feet of Water Meters of Water kPa 0 0 000 0 000 0 000 5 11 537 3 516 34 474 10 23 073 7 033 68 948 15 34 610 10 549 103 421 20 46 146 14 065 137 895...

Page 57: ...analog means there will be a residual non linearity i e the non linearity is not completely removed The following non linearity graph illustrates why a two point calibration zero and full scale is man...

Page 58: ...rections If a pressure transducer has zero pressure applied then 10 PSI then 22 PSI then 10 PSI the difference between the two 10 PSI readings would be a measure of the pressure hysteresis of the tran...

Page 59: ...end the command out over the SDI 12 bus The 8200 will then display the response to the command Logging data from the M1 or M2 commands or from addresses above 9 Beginning with version 3 3 of the softw...

Page 60: ...re of an ACCUBUBBLE that has been installed at address 5 the following command must be issued 5M2 With the 8200 family the logged parameter came be named to help identify the data on future visits or...

Page 61: ...ugh we pride ourselves on handling 95 of application related questions over the phone we maintain constant contact with our Integrated Systems Division and Engineering Division for additional assistan...

Page 62: ...all pay transportation for the return of the repaired equipment to the customer when the validity of the damage claim has been established Otherwise Sutron will prepay shipment and bill the customer A...

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