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Measuring Current with an ADC11

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Measuring Current with an ADC11

Postby Jasper » Mon Mar 17, 2008 9:35 pm

Can anybody help,

I am waiting for my adc11 to arrive. i am intending to measure the output 4-20Ma current from 4 shock sensor units.

Can anybody give me a heads up as to how to set up the unit or what i should look out for etc, i have read some of the posts and they do not go into to much detail, this is fairly new to me as i normally rely on dedicated measuring devices for the sensors we use, however i am keen to move into different areas and experiment

Many thanks for any help

Jasper
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Postby ziko » Wed Mar 19, 2008 1:28 pm

Hi Jasper have you had a look at the ADC11 terminal board instructions

http://www.picotech.com/document/pdf/ad ... ons-en.pdf

Section 2.2. gives a description on what you need to do measure current.

Also the PicLog Manual will give you an idea of how to set the unit up:

http://www.picotech.com/document/pdf/plw044.pdf

To give you a brief idea of how the softwre works, you initially create the settings, via File->New Settings. Once you have done that you create a data file to record the data to, via File->New data.

You may also be interested in using the scaling section when creating your settings, please have al look at section 5.1.8.2 Parameter scaling for more information.

Hope this helps.

Kind regards
Ziko

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Postby Guest » Wed Mar 19, 2008 1:55 pm

Thanks zICO

i will take a good look later today

Jasper
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Postby Guest » Wed Mar 19, 2008 2:02 pm

the sensors i am using are shock pulse and give a 4-20 Ma output so the highest recorded current would be 20 Ma

however when you measre the voltage across the outpu terminals you also get 22vDc

The adc only takes up to 2.5 volts so do i need to carry out the process as described in measuring voltage as well?

Thanks

Jasper
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Postby ziko » Thu Apr 03, 2008 11:59 am

Hi if there is no load the voltage will rise to approximately the supply voltage that is why you need a load resistance of say 120 ohms. This will limit the voltage to 480mV at 4 mA and 2.4V at 20mA.

Hope this helps.

Kind regards
Ziko

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