How should Sensirion SHT71 be wired to SCB-68A connector block?

[abright]

Hi all,

I just got a Sensirion SHT71 for humidity measurement. I am new to digital I/O field so I feel unclear about how to connect this sensor to the DAQ. 

The DAQ I am using is PXI-6225 hooked up with a SCB-68A connector block. 

And the sensor has 4 pins (1-SCK: Serial Clock, 2-VDD: Source Voltage, 3-GND, 4-DATA (bidirectional))

Detailed manual can be found here http://www.sensirion.com/nc/en/products/humidity-temperature/download-center/?cid=8574&did=68&sechas...

So I am wondering what are the corresponding connectors on SCB-68A to those pins of the sensor. I can see the GND goes to the D GND for sure and the VDD is supposed to be connected to +5V. And I am not sure to which two connectors SCK and DATA should connect...

Reference label of SCB-68A can be found here: http://digital.ni.com/public.nsf/$CXIV/ATTACH-AEEE-8ZRTL5/$FILE/S_Series.pdf

Thanks.

[IronBrotha]

Hello abright,

I have been looking at your case the whole day, analizing the circuitry of your application. 

From what i can tell from the Reference label of SCB-68A : http://digital.ni.com/public.nsf/$CXIV/ATTACH-AEEE-8ZRTL5/$FILE/S_Series.pdf and the user manual: http://www.ni.com/pdf/manuals/375865a.pdf and the datasheet of your sensor, I can see that the output is a current signal. there we must create a simple circuit so that the DAQ device can be able to read the values. From what I can see of the datasheet, the output is digital therefore we need a Digital input to read the measurements, therefore on page 4-9 and page 4-10 of the user manual you can see the circuitry used to read digital inputs of a sensor. therefore what we can try to do is connect the sensor output to a a resistor in order to see the output voltage across this resistor. Simple Ohm's Law V=RI.   Therefore you can see wherethe DATA which will be the output pin will be connected to pin 11. As for  the SCK  it is only used to sync the sensor to the measurement device, therefore I would assume that pin 10 which corresponds to PFI 1/AI REF TRIG which will be the reference trigger will be used to sync both of devices in case you need this configuration. VDD will be the source of energy for the sensor. i would suggest not to use the full 5V, I can recall seeing something like this on the web about not connecting the sensor to the full 5V. and GND is the reference voltage. For the pin out configuration please check the Figure 4-13. SCB-68A Circuit Diagram for Digital Input Attenuation on the user's manual.

If you have further questions regarding the pin out of the device please let me know. 

Kind regards,

IronBrotha

AE CR