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An innovative approach to Wireless Monitoring

In horticulture, food production, industry or countless other processes, data needs to get from “Point A” to “Point B”. Of course wiring can be run, but often that is not possible or convenient.
Whether it’s looking at the temperature of a chiller, checking for melted plastic or detecting frost in a vineyard, wireless may work for you.

Most of us use wireless technology daily without much thought; wireless keyboards, garage door openers and cell phones are almost universal.  Wireless for remote monitoring processes presents its own unique challenges.
We look at a couple of examples, examine the challenges and discuss some solutions.

 The Cherry Orchard 

Cherries are a high value crop.  They are affected by frost, moisture, sunlight and temperature.  By monitoring the data, damage to crops due to adverse weather conditions can be minimised or avoided.
What are some of the challenges faced by this farmer?
  • It’s outdoors.  Any solution must be weatherproof
  • It’s a long way away.  From the orchard to the farmhouse is about 1 kilometre.  Wire is not going to be practical
  • It’s even further!  The farmer goes to town and still needs access to his data
  • It takes a while.  Cherries blossoms in spring and produces fruit in summer.  Knowing the temperature and moisture trends in late spring might be important (ie data to be logged)
In this case we place a wireless temperature logger in the orchard where parameters such as barometric pressure, leaf-wetness, sunshine, or rainfall can be monitored back at the farmhouse where the data is logged and viewed on a PC.
Because the farmhouse is 1-kilometre away, in this case we’d need to place a waterproof repeater at a point between the orchard and the house.
Once armed with the required data the orchardist can make informed decisions on crop management.

 Chart and Temperature Recorder (CaTR) Replacement.

The paper chart recorder used to be one of the standard instruments for food manufacturers to monitor their processes for compliance and verification purposes. 

Scarcity of replacement consumables (pens, charts etc.) and the fact that these loggers were mostly mechanical, means that fewer and fewer working units remain in use.
The Delta Ohm system is an almost ideal solution for several reasons.  In most cases, temperature probes that are already there can be re-used with the new system and wireless connectivity makes for easy integration.
HD35 app1 HD35 app2

 Compliance with NZ regulations

The radio frequencies used in New Zealand for wireless devices are quite different to almost all the others in the world.  Under new laws (February 2015) anyone selling radio transmitting equipment in New Zealand must be a Radio Frequency Service, “Responsible Supplier”.
It’s important to note that radio transmitter products made for sale anywhere else in the world are probably not operating legally in New Zealand unless they have been specifically made for this market. 
Homershams applied for and were accepted as a Responsible Supplier in 2015 (Homershams RS# E4047). All radio transmitting equipment supplied in New Zealand should have this logo somewhere visible.


Once the data from the sensors reaches the base unit and/or PC there are a number of ways to access it, or network it further into other, or already installed systems.
For example options exist for:-
  • Cellular communication (for example one might be alerted after hours if freezers fail)
  • MODBUS (aka RS485) (for example connection into an already established SCADA system)
  • Remote Login e.g. Microsoft RDP, LogMeIn, TeamViewer etc.
  • TCP/IP networking within an office
HD35 Network
USB, Ethernet & Wi Fi
Cellular & USB

What if……………..? 

  • Sometimes computers restart (or even upgrade to Windows 10 without asking! (As happened to one of our Delta Ohm customers last week))  What happens to my data if my PC fails, reboots, drops out of wireless range or is inadvertently switched off?  Happily the individual loggers (ie the wireless transmitters) store the data within themselves (typically 140,000 data points) and background update to the PC once the issues above are resolved without further intervention. 
  • What if my range is too great between transmitter and receiver?  A repeater or repeaters can be placed between the transmitters and receivers increasing the range to a great distance. 
  • What if I wish to export my a particular data range (e.g. Monday 7th to Wednesday 12th) into a graph and into an Excel spreadsheet?  Select the date range and press “GO”.
  • What if I don’t have power out in the orchard?  No problem, the transmitters run on battery’s and dependant on the interval of recording, will lasts months or even years. 
  • What if I need an alarm to let me know if something is wrong? Wireless alarm modules can be added to the system giving two relay outputs per unit for signalling alarm events. 

 Graphical Display 

The individual transmitters can have as an optional extra, very sharp LCD displays which can display all the measured data as well as information about the radio signal strength back to the receiver /base station (RSSI).
At the PC end, very detailed data is available for review, or a simple “Monitor” screen can be selected for a simplified, easy-to-glance-at summary.
HD35 Software

What kind of data can I measure? 

Almost anything!  Specialist loggers for Temperature, Humidity, Differential Pressure, Weather Stations, UV and Photo-metrics are available, but there is also a multi-channel universal input model which can take any one of hundreds of industrial transducers.

Postscript - Application Note 

Because the loggers can operate stand-alone as well as direct to PC, they can be used in some novel applications. Consider the following example.
A food manufacturer needs to monitor the cold chain management of product from their factory to the supermarket and the stock they pick up at the supermarket for return.  A temperature logger mounted in the truck records 140,000 data points with date and time stamps. On return to base the stored information is automatically downloaded to the designated supermarket PC.  A complete study of the temperature profile from source to terminus is readily available.
HD35 app3
The 900-Mhz band used by the Delta Ohm system is superior in range and interference resistance to any 2.4 GHz device, Wi-Fi or ZigBee (for the same Power Output). 
We have a basic 3 channel package readily available or we can advise on a custom system to meet your specifications. Click here to go to the product page or contact us to discuss your requirements, ask questions or to request a demonstration.   
Homersham’s are 100% NZ Owned and have been supporting New Zealand business for over 75 years
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