Using LV on a host PC with the NI WSN-3212 with the Sensorex DO6400 Dissolved Oxygen Sensor
The LabVIEW Project Explorer Window can be used on a host computer to read data from the WSN node. Right click on the NI WSN-3212 node in the Project Explorer to configure its properties. Under the channels tab, in the range drop down menu, configure thermocouple (TC) channel for voltage input by selecting -0.73 to 0.73 Volts. Under the node tab, set the node sample interval (seconds) hardware configuration setting to an interval appropriate for your application. A typical sample rate for DO applications might be one sample every hour, or 3600 seconds.
You can read the Sensorex DO6400’s data into LabVIEW by reading the current value of the shared variables available from the NI WSN-3212. Simply read the analog input channels that the Sensorex DO6400 is wired to, and then scale the acquired analog signal to the appropriate dissolved oxygen level. You will also need to calibrate the sensor as described in the sensor’s User Manual. This involves letting the sensor sit in open air to determine the voltage returned for 100% saturation. Using this reading and the fact that 0 volts will be returned for 0% dissolved oxygen, you can create a scaling factor that can be used to convert from voltage readings to % saturation of dissolved oxygen.
In the block diagram pictured below, calibration of a test DO sensor resulted in a scaling coefficient of 2790. Therefore, the % dissolved oxygen will equal the measured voltage multiplied by 2790.
Figure 4. LabVIEW block diagram to acquire, scale, and display wireless data from DO64000
Using the LabVIEW WSN Module on the NI WSN-3212 with the Sensorex DO6400 Dissolved Oxygen Sensor
With LabVIEW WSN, you can download and run LabVIEW VIs on the programmable version of the WSN node for local data processing and control. For example, you could perform the data scaling to engineering units locally on the node itself, returning Dissolved Oxygen concentration directly, instead of volts.