1. Veris Industries PW Series Wet Media Pressure Transducer
The Veris PW Series wet media differential pressure sensor is designed to measure pressure across pumps, filters, heat exchanges, compressors and other non-corrosive wet media applications.
Figure 1: Veris PWL Series Pressure Transducer
The PW Series sensor measures the difference between two pressures introduced as inputs to the sensing unit. The sensor is installed on a duct or pipe across a pump, filter, heat exchanger, compressor, or other non-corrosive wet media. The sensor calculates the differences between the pressures and outputs a voltage that corresponds to the value.
2. Wireless Differential Pressure Measurement
With NI WSN you can remotely monitor a network of sensors over large areas. By combining the PW sensor with the WSN-3202 voltage node it is possible to monitor differential pressure in different areas of a building, all from one location. This eliminates the need for multiple monitoring systems or computers; thus, creating a control system that is ideal for monitoring differential pressure.
System expansion is also made easy when using the NI WSN. Sensors and WSN nodes can simply be added as needed.
3. Connecting the PW Series to NI WSN-3202 Node
The PW Series sensor can output either current or voltage signals. This document discusses the use of the PW sensor in voltage mode, with the default voltage range set to 0 to 10 V. To configure the PW sensor for 0 to 10 voltage mode, move jumpers JP1 and JP2 to the right position. The document also assumes that JP8 is set to Normal, JP7 is set to Normal, JP6 is set to Normal, and JP3 is set to Slow Surge Damping. The Range should also be set to A, which corresponds to 0-100 PSID.
The NI WSN-3202 voltage node has 4 single ended analog inputs. The voltage node also has a 12V voltage output that is dedicated for sensor powering. The PWLX04S sensor requires 12 to 30VDC power, with 125mA max current draw, for this reason an external power supply is required.
Connect the Power input of the PWLX04S to the positive terminal of the power supply. Connect the COM input of the PWLX04S to the AI GND of the WSN-3202 node and the negative terminal of the power supply. Connect the Signal output of the PWLX04S to AI0 on the WSN-3202 node.
Figure 2. Connecting PW Series Sensor to WSN-3202
4. Programming NI WSN for use with the PW Sensor
Using LabVIEW on a host PC with the NI WSN-3202 with the PW Pressure Transducer
LabVIEW makes the programming for the PW Series sensor applications very straightforward. First, the input range for WSN-3202 analog input channels needs to be set to -10 to 10 Volts to comply with the PWLX04S output voltage range of 0 to 10 volts. This can be set in the Data Configuration section of the NI WSN-3202 Properties window. Next, the sensor powering needs to be enabled. This can be done in the Channel Attributes section of the NI WSN-3202 Properties window. Set the attribute to “Sensor Excitation” and the Value to “25 ms before sampling”.
With the WSN properties set, the application building can begin. Each I/O variable on the WSN voltage node has an I/O variable associated with it in the LabVIEW Project. The AI variable for the pressure channel should be dragged onto the block diagram, in this case AI0. This variable outputs voltage values between 0 and 10 volts and this data needs to be scaled to the appropriate values. The pressure output of 0 to 10V linearly maps to 0 to 100 PSID.
Below is an example block diagram for the PWLX04S application. This example gets the voltage reading from the AI variable and displays it on the front panel. It also applies the scaling and displays this information. The example program can be found at the following link: Link to EPD example program .
Figure 3. Block Diagram for PWLX04S with WSN
5. Using LabVIEW WSN Embedded Programs on the NI WSN-3202 with the PW Series Sensor
With LabVIEW WSN, you can download and run LabVIEW VIs on a programmable WSN-3202 node for local data processing and control. For example, you could perform the data scaling to engineering units locally on the node itself, before it is sent to the host computer.