Interfacing Sensors with Process Controller

You can quite easily interface sensors with Process Controller. Process Controller can be interfaced with pH probes, temperature probes, dissolved oxygen probes, and pressure sensors. Below is an auto tutorial on interfacing a pressure sensor with process control software.

Auto Tutorial for Pressure Sensor

This portion is part of a larger tutorial to set up a sample laboratory process of adding chemical to a tank and the start of which can be found here.

Before starting this tutorial, plumb your large tank to ensure that it can drain to the sink.

In this section of the tutorial, we wish to add a pressure sensor to measure the change in tank water level over time.

Step One: Plug in Pressure Sensor to Sensor Box

Find a 7 kPa pressure sensor and plug it into the Sensor Box. Note the location of sensor by the number.

Step Two: Add the Pressure Sensor to the Experiment

Plug the pressure sensor into the tank at the bottom. Fit a 0.25" O.D. inflexible tubing over the end of the pressure sensor that should be in contact with the water as shown in the picture below.

Step Three: Open Appropriate Sensor Calibration File in Process Controller

Navigate back to the configuration screen and click on "Sensor configuration and calibration" as shown in the figure below.

Next in the sensor configuration and calibration screen, click insert sensor. In order to utilize this sensor we first have to calibrate it. Remember that the type of sensor we selected was a 7 kPa pressure sensor, so we should choose a calibration from one of the 7 kPa files.

Click on the far right folder highlighted in the figure below to open an existing sensor calibration file. We want to select "cm of water.smc" as the calibration file which will read the water height in the tank from the pressure sensor in centimeters of height.

The path directory to find this calibration file is: enviro\enviro on enviro\Software\Data Server\Sensor Calibration\7 kPa

Step Four: Calibrate the Sensor

The next step is to take note of where you plugged in the sensor. It should be plugged into the top row and there should be a number value above.

For the environmental processes teaching laboratory, the benches are in Mod 1. In the AguaClara labs, the addresses are Mod 4. You should select the module and then the channel as indicated by the number into which you have the sensor plugged.

After you have accomplished this, you should try to make sure that the pressure sensor is sensitive to changes. Try applying pressure to the side facing out on the pressure sensor. There should be a measurable change in pressure. If you are convinced that you are in the right port and see no change in pressure, try pouring in about 2 L of water into the larger tank. You should see a difference now.

The next step is to zero the pressure sensor. With the tank fully drained of water, "zero" the sensor. The pressure reading should be close to zero.

Next add about 2 L of water to the larger tank. The pressure sensor should now read a water height of approximately 3.5 cm. Confirm this.

Click "OK" to navigate back to the configuration tab and we're done with this tutorial. The next tutorial is data acquisition and analysis