Wireless link enables pump control

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December 2014 Data Acquisition & Telemetry

Agri Seeds Research Center in Canterbury New Zealand commissioned Define Instruments to provide a wireless link between a reservoir and a pump station. The site evaluation showed that there was no line of sight between the reservoir and the station and that there were significant RF obstacles in the form of large trees and buildings on the site.

Taking the evaluation into account, Intech decided to install a Define Instruments P2P (point to point) wireless system. Three devices were required to complete the job. These were the WG-P2P-I, which takes two isolated input signals including temperature sensors, process inputs and frequency, as well as four digital inputs. In this case it was used to measure a single 4-20 mA output signal from the reservoir level sensor. This signal was converted to a digital message and transmitted wirelessly to a WG-P2P-R repeater. The repeater automatically forwarded this digital message to a WG-P2P-O output device. This output device reconstructed the signal into a 4-20 mA output that was wired to an existing pump controller.

“Commissioning the system was straight forward,” commented John Green the Intech installer. “The radio system is based on self-configuring Zigbee technology and within minutes of power-up the system was functional. However, we found out from the input units front LEDs that the RF signal link quality was poor. To overcome this we changed the antennas to higher gain versions to punch through the obstacles. Once this was done the signal link quality LEDs indicated maximum quality and we were confident that we had achieved a reliable setup for our customer.”

Define Instruments Rolla Afrogheh suggested that it would be possible to reduce costs in a new installation by programming the input device as a controller to control the pump directly, removing the need for a separate pump controller. The digital inputs and outputs are transparently transmitted between the input and output devices. So in the case when the input is set-up as a controller the output relay states are automatically routed to the output devices relays.

For more information contact Dylan Swartz, Define Instruments South Africa, +27 (0)87 945 2700, [email protected], www.defineinstruments.co.za

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Data Acquisition & Telemetry

Wireless link enables pump control

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