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The USB DrDAQ and the auto detect resistors

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The USB DrDAQ and the auto detect resistors

Postby Glovisol » Sun Nov 02, 2014 5:09 pm

I examined three PICO publications as follws:

1) USB DrDAQ Data Logger - User's Guide.
2) PicoLog Data logging software - User's Guide.
3) PicoLog Self-Help Guide.

The most detailed reference to the Auto-Detect resistors can be found in reference 1) above. On page 32 we read:

Auto-Detect Auto-detect resistor is placed between Ground (pin 2) and Signal Detect (pin3). The value of the resitor should be selected from one of the following common values: 1k0, 2k2, 3k3, 5k6, 7k5, 10k. It is necessary to have an auto-detect resistor so that the software can automatically scale the input signal into the property it represents.



Very good, all is well, save that nowhere in Pico publications we can find what "common resistor values" correspond to which "input properties" to be represented.....

Is there perhaps some other Pico publication I have missed?
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Re: The USB DrDAQ and the auto detect resistors

Postby Martyn » Mon Nov 10, 2014 1:37 pm

If you continue on and look at Page 33 you will see the dds file description as shown below

[Scale1]
Resistor=1
LongName=CustomTemperature1
ShortName=TempC
Units=C
MinValue=-40
MaxValue=120
OutOfRange=0
Places=1
Method=0
IsFast=Yes
NoOfPoints=32
Raw1=2.385
Scaled1=-30
...
Raw32=1.32
Scaled32=100
[Scale2]
Resistor=2.2
LongName=CustomTemperature2
ShortName=TempF
Units=F
MinValue=32
MaxValue=160
...
[Scale3]
Resistor=3.3
LongName=CustomLight
ShortName=Light
Units=lux
MinValue=0
MaxValue=20000
...


In this example

Scale 1 Resistor 1k0 Custom Temp1
Scale 2 Resistor 2k2 Custom Temp2
Scale 3 Resistor 3k3 Custom Light

but these can be changed to meet your requirements
Martyn
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Re: The USB DrDAQ and the auto detect resistors

Postby Glovisol » Wed Nov 12, 2014 4:25 pm

Dear Martyn,

Thank you!! Got it now. Each resistor value identifies the corresponding probe.
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