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AD-16

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AD-16

Postby tejalpatel » Mon Jun 13, 2005 2:43 pm

I am using the AD-16 pico data logger. I want to design the circuit board in order for it to read pressure that is being taken by a pressure transducer with a digital meter. The data logger should take the pressure readings every 30 seconds, and then input into a microsoft excel sheet. How can I design the board in series and have the computer take readings at the same time? Thanks for your help.
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Postby Sarah » Tue Jun 14, 2005 9:10 am

Hi

Thank you for your post.

The conditioning you will need to apply to the signal will depend on the characteristics of the signal. What type of output is the pressure transducer giving? Is it a digital output or an analogue one? What size is it?

You can set the software to take a reading every 30 minutes - this would not be a problem. You could program your own software in Excel to take the readings if you wish. We supply drivers and basic examples for doing this.

Hope this helps

Best Regards
Sarah
 

Postby tejalpatel » Tue Jun 14, 2005 11:55 am

The digital meter outputs a 4-20 mA signal, the pressure transducer attached to it reads pressures between 0 and 15 psi. It is an analog output.

The examples are hard to find and that is what i'm actually looking for. Even after going to www.picotech.com/software.
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Postby Sarah » Thu Jun 16, 2005 10:16 am

Hi

Thank you for your post.

To connect a 4-20mA signal you quite simply need to use a shunt resistor. You can work out the appropriate value of the resistor with the V=IR equation.

If you have an ADC-16 terminal board then there are places for using resistors on this. You will need to see which channels have the correct placings.

Hope this helps

Best Regards
Sarah
 

Postby tejalpatel » Thu Jun 16, 2005 6:25 pm

is a 10,000 ohm resistor too big for this circuit board. i have an electrical resistance of 20 ohms being applied from my digital process meter.
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Postby Sarah » Mon Jun 20, 2005 9:09 am

Hi

Thank you for your email.

Yes, 10,000 is too big. You need something more in the region of 100 Ohm - this would be fine for your application.

Best Regards
Sarah
 

Postby tejalpatel » Wed Jun 22, 2005 2:54 pm

thank you for the help with the resistor, the device is finally picking up the signals. i hope this is my last question, is there a formula that the pico logger uses in order to convert the current i'm sending through into volts. this is besides the basic V=IR equation.

Tejal
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Postby Sarah » Thu Jun 23, 2005 10:48 am

Hi

Thank you for your post.

No, the whole thing is based on V=IR. This is because you should be measuring the voltage across the resistor. As you then know the value of the voltage and you know the value of the resistor, you can calculate the current.

Hope this helps

Best Regards
Sarah
 

Postby tejalpatel » Mon Jul 18, 2005 8:02 pm

I have a new question. Is it necessary to use the counts to volts conversion for the pico board? What exactly is the board reading as in counts? What does the stand for? Am I to assume a 16 bit resolution? what does the n in (2n-1) in the help file stand for? My conversion is not occuring correctly in my excel program. When I apply 0.5 psi it reads out 51 mmHG, I know everything else is correct. So I would like more information on the counts and what it stands for according to the picolog manual?
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Postby Sarah » Wed Jul 20, 2005 9:32 am

Hi

Thank you for your post.

This piece in the help manual is for when you are writing your own software and tells you how to convert the raw data from the unit into a voltage. If you are using Picolog and converting the voltage that you already have then you do not need to worry about this.

Best Regards
Sarah
 

ADC-16

Postby Guest » Wed Jul 27, 2005 8:13 pm

I have written my own software. I put into the program that i am using 16 bit resolution. Does the count convert over the 65535 conversion? I am asking is that can't i get a number of voltage over 65535, such as 130,000 or something like that.

I can elaborate if this doesn't make any sense. Thank you for your help.

Tejal
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Postby Sarah » Thu Jul 28, 2005 11:05 am

Hi Tejal

Thank you for your post.

Could you elaborate on this a bit please? I will need to talk to our software engineers about this and would like ot give them as much information as possible.

Many Thanks
Sarah
 


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