Hello
Does anyone have experience with connected Accelerometer to Datalogger CR1000.
I have VIBRATION SENSORS "Model 3058A Accelerometer".
http://www.meas-spec.com/product/t_product.aspx?id=9369
Accelerometer use piezoresistive technology in a 4-Arm Wheatstone
Bridge configuration (Full Bridge). I connect accelerometer to datalogger by manual.
In CR_Basic I use "BrFull(....)".
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BeginProg
Scan (1,Sec,3,0)
Battery (BatteryV)
SubScan (10,mSec,0)
BrFull(....)
Next SubScan
NextScan
EndProg
-----------------------------
I don't know which instruction I have use in CR Basic for correct connected accelerometer.
I have problem with storing data in small intervals too - (100 mSec,10 mSec,...).
Thank you.
In the data sheet for the 3058A Accelerometer is that the Accelerometer requires an Excitation Voltage between 2.7V and 12V DC.
CR1000 Datalogger has the Excitation Voltage 2.5V DC. It is maximum.
This cause may be the reason why it does not work.
I believe Cyril has been in touch with one of our staff who has recommended he contact the manufacturer of the accelerometer to check the 2.7 V limit. Other information on their website implies their sensors will run down to 2V but they recommend contacting them first. This seems to be because the temperature compensation technique they use may not work so well at low voltages.
I would say there is a good chance they will run at 2.5 V anyway. If you want to run fast and also as we don't know the details of the temp compensation, I would advise to not set the option to do a second measurement with excitation reversal. You also need to allow at least 1 ms settling time (manufacturers data).
To avoid the low excitation altogether and most issues with settling/warm-up time you could power the sensor from the 5V output on the logger continuously and then just make differential voltage measurements of the output. The 5V output is not a precision output, so for best accuracy you could measure it with a single-ended channel on the logger and use that to work out a scaling factor.
With the right program you should be able to make mesaurements on one channel at 100 Hz, or by using special programming techniques you can measure at around 250 Hz continuously or even faster in bursts.
OK.
Thank for answer.I am trying to write a program with two different scan intervals (1Hz and 100hz).
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Public Accm
'########## Declare T109 ##########
Public T109_C
Public Strain
Public Vr1000
Public GFRaw
Public GFAdj
Public BrZero
Public CKnown
Public CReps
Public ZMode
Public QBSSMode
Public CIndex
Public CAvg
'########## Declare Transuder S350 ##########
Units T109_C=Deg C
Units Strain=microstrain
Units Vr1000=mV/V
Units Accm=mV/V
DataTable(C,True,-1)
DataInterval(0,1,Sec,400)
'CardOut (1,-1)
Average(1,Strain,IEEE4,False)
EndTable
DataTable(A,True,-1)
DataInterval(0,10,mSec,400)
Average(1,Accm,IEEE4,False)
EndTable
DataTable(B,True,-1)
DataInterval(0,1,Sec,400)
Sample(1,T109_C,IEEE4)
EndTable
BeginProg
CIndex=1 : CAvg=1 : CReps=1 : GFRaw=498.6 : GFAdj=GFRaw
Scan(1,Sec,3,0)'Set program scan interval to 5 second
Therm109(T109_C,1,1,1,0,_50Hz,1,0)
BrFull(Vr1000,1,mV2_5,2,2,1,2500,True,True,0,50,1,0)
StrainCalc(Strain,1,Vr1000,BrZero,4,GFAdj,0)
FieldCalStrain(43,Strain,1,GFAdj,0,QBSSMode,CKnown,CIndex,CAvg,GFRaw,0)
FieldCalStrain(10,Vr1000,CReps,0,BrZero,ZMode,0,CIndex,CAvg,0,Strain)
CallTable(B)
CallTable(C)
SubScan (10,mSec,100) BrFull(Accm,1,mV2_5,3,3,1,2500,True,False,0,250,1,0.12)
CallTable(A)
Next SubScan
NextScan
EndProg
------------------------------
And result:
Compile fail:
Scan Intrval 10000000 too short for measrurement by 53900uSec.
Any help or suggestions would be very appreciated.
If I use SlowSequence then Scan in SlowSequence not run.
------------------------------
BeginProg
CIndex=1 : CAvg=1 : CReps=1 : GFRaw=498.6 : GFAdj=GFRaw
Scan(10,mSec,100,0)
BrFull(Accm,1,mV2_5,3,3,1,2500,True,False,0,250,1,0.12)
CallTable(A)
NextScan
SlowSequence
Scan(30,Sec,100,0)
Therm109(T109_C,1,1,1,0,_50Hz,1,0)
BrFull(Vr1000,1,mV2_5,2,2,1,2500,True,True,0,50,1,0)
StrainCalc(Strain,1,Vr1000,BrZero,4,GFAdj,0)
FieldCalStrain(43,Strain,1,GFAdj,0,QBSSMode,CKnown,CIndex,CAvg,GFRaw,0)
FieldCalStrain(10,Vr1000,CReps,0,BrZero,ZMode,0,CIndex,CAvg,0,Strain)
CallTable(B)
CallTable(C)
NextScan
EndSequence
EndProg
------------------------------
Thanks for reply.
Campbell sci don´t offer accelerometers for sale directly.
Could something recommend me accelerometer available for bridge monitoring compatible with cr1000?
Peak acceleration that you want to measur: Range (g) ±2
Maximum frequency of interest: 150 Hz
Minimum temperature at which you would acquire data: -40°C
Maximum temperature at which you would acquire data: +125°C
Desired excitation voltage: 0-2.5 V
Single ended or differential output
Electrical output : wires
Sensitivity: 8 - 16 mV/g
Thanks
Measurement Specialties
http://www.meas-spec.com/vibration-sensors.aspx
PCB
www.pcb.com/TestMeasurement/Accelerometers.aspx
However, the CR1000 cannot sample at 300 Hz which
is what would be required to obtain resolution of
150Hz events. The fastest I would recommend driving
the CR1000 for this measurement is 50Hz (1 channel)
and then you would be able to resolve 25Hz events.
For more than one channel, you would have to move to
the CR3000 (where you can do more than one channel or
also may be able to get 100Hz sampling to work OK for
one channel).
If the 150Hz is a hard requirement, you have to move
to the CR9000X
https://www.campbellsci.com/cr9000x-series
Can be used modul(the AVW200 Vibrating Wire Spectrum Analyser or The CDM-VW300)as interface between sensors(acclerometer) and datalogger cr1000?
Thanks
If you find a company that manufactures a "vibrating-wire accelerometer", then you could place the AVW200 series (AVW2xx) between that sensor and the CR1000 and get it to work. However, the fastest mode that the CDM-VW300/305 can run with the CR1000 is 50Hz (8 channels). The AVW200 can only make a reading once every 2 seconds. With a CR3000, you could get the CDM-VW300 to work at 100Hz.
However, I'm skeptical about the chances of your finding a "vibrating-wire accelerometer". That would be pretty uncommon. Much more common is the terminology of calling an accelerometer a "vibration" sensor, which is something quite different from a "vibrating-wire" sensor.
What might make more sense is to look at a vibrating-wire extensiometer or strain gage. You might be able to obtain readings that would provide you with the same information, or which would enable the same information to be calculated from the sensor's output.
aps mentioned that with some special programming you may be able to get a 250Hz measurement, either continuous or in bursts. It may make the most sense to move in that direction with just a "regular/mainstream" accelerometer.
If you always wish to learn more about accelerometer consult this site : http://www.directindustry.com/industrial-manufacturer/accelerometer-62014.html