Design help for an orchard irrigation system

Hi all,
I’m about to start an automation redesign of an existing orchard irrigation system on my ranch. The current system distributes wi-fi to two pump locations and control/status instructions are routed to about 30 24VAC solenoids throughout the 96 acre orchard via buried copper control cables connected to a couple of ProXR relay banks. It all has been working great for years, EXCEPT, some of the copper has become broken and re-burying is impractical. (Some of the copper is over 25 years old.)

I am considering installing a solar-powered communication/control tower at each solenoid connected with via a wi-fi mesh network. Each tower would have a small solar panel to charge a 12V battery, a 12VDC->24VAC transformer (to supply voltage to the solenoids) and a single relay device that would control the solenoid.

I was wondering if anyone here has experience with this sort of application and would be willing to share their thoughts.

How would the solenoids be controlled? Manually opened/closed via a User interface or would this be automated?

Utilizing WiFi communication for devices like that sounds very costly. Covering an area like that really isn’t what WiFi was designed for. I would think controlling the relays over a 900mhz long range wireless connection would be more feasible. However in order to recommend appropriate devices I would need to know more about the control aspect of this application.

Hi Travis,
Turns out you helped me about 6 years ago setting up my existing system with the ProXR mechanical relays.

My orchard is laid out with the 24vac solenoids spread out approx 700’ apart in the east/west and north/south directions and about 990’ diagionally. Wi-Fi is currently distributed to 2 pump locations using Ubiquity Nanostation access points and stations. There is a hill between the base station and the pumps, so I use the Ubiquity antennas to go over the hill and relay signals to each pump.

My initial idea would be to install a 5amp relay controller (PR60-7_R15PL) equipped with a 900MHz XBEE-Pro communications module (XBP9B-DMST-002). I’d extend the antenna wire up the mounting poll which will terminate above the top of the tree canopy, along with a small solar panel to charge a small battery, power the relay and a transformer (12vdc->24vac).

I have developed an automated control system that I use to schedule, run and log timed irrigation sets. (A single irrigation set may involve opening up to 5 separate relays)

I’ve never worked in a mesh environment, but I gather that I will need some sort of interface device at one of my Ubiquity antennas to link the mesh network to the pre-existing wi-fi network that connects to my control software.

Does this seem workable? What digimesh interface would be appropriate to link the mesh network to the wi-fi network? Is there another option that might achieve this?

Excluding the interface, it looks that a per solenoid cost for the relay and XBEE would be around $160/unit.

Thanks for your insights.

This WiFi Modem could be connected to your Network and would provide connectivity to the Mesh Network:

Your software will establish a TCP socket connection to this modem over the network and send commands to the 900mhz digimesh controllers through it:

Digi has documentation on the DigiMesh protocol here:

Please take a look and let me know if you have any questions on this.

Thank you,
Travis Elliott

I think I’m getting it. But I do need some clarifications.

I would most likely install the “mega modem” at one of my pump sites. That site has a 4-port ethernet hub with available ports. So the modem I would need would need to have an ethernet connection rather than wireless.

I would also have to purchase an XBee Pro 538 option for the modem for it to connect to the digimesh network. Correct?

By plugging the modem into the existing ethernet, all communication back to the server would occur over the 5MHz Ubiquity network. I could then run the XTCU software back in the office to configure the components. Is this correct?

Finally, the mega modem documentation talks about communicating with sensors, which I am not doing. I am communicating with a 1-channel relay board, PR60-7_R15P, configured with the XBee-Pro communication module. I’m assuming this will work just fine, but I’d like to have you verify that.



We have an Ethernet Modem here:

This modem can be purchased with the 900 mhz(North America) module. Do be sure to note in Order Notes during Checkout: “Ethernet modem is to be used with ProXR relay controllers, do not enable Encryption option on Modem”. This will ensure it is compatible with your ProXR Relay controllers.

XCTU unfortunately only works over a COM port. Connectivity with this modem will be via a TCP socket over port 2101. However if you are crafty you can install a TCP to VCP driver on your computer which will mount a virtual COM port on your computer which will port all communication to a TCP socket connected to the Modem. This would enable you to communicate with the Modem from XCTU.

Yes, the Ethernet modem and Mega Modem are a part of our Enterprise line of products which are mainly sensors. It however can be used with ProXR relay controllers as well.

Thank you,
Travis Elliott

Perfect, thank you.

Since getting my original system up and running 6 years ago with ProXR relays, I haven’t had occasion to visit much. It seems like your sensor line has really expanded. After I get my relay replacement project finished, I might be interested in assembling a weather station to place in my orchard. Am I correct that would need a 2nd modem with the encryption enabled, or, can the sensors be enabled w/out encryption? I am in a rural environment and am not really concerned about encryption.

Thanks for all your help.

In that case it might be best to go a different direction with the system. If you want to have relays and sensors it might be better to use something like this in place of the ProXR boards which is more compatible with the Enterprise line of products:

Then replace the Modem with this device:

If you do this you have built the backbone a very complex/capable system can be built upon.

I think in my case it would be more cost-effective to stick with the 1-channel, 5amp ProXR relay with an XBee communication option and the ethernet modem with XBee module, mainly because each station needs only 1 relay and I need 30 stations to cover the orchard. The solenoid only pulls 0.4 amp inrush and 0.2amp holding.

Please clarify for me, if I have the XBee communication module in both the relay and the modem, do I have to have encryption disabled on both? You indicated I needed to specifically request it be disabled on the modem. Why not on the relay side? Or, is it already disabled when installed on the relay?

Pending your response, I think I’m ready to purchase the modem and 1 relay for a proof-of-concept setup and to enable me to modify my control software to communicate. Once that is shown to work, I’ll do the remaining 29 relays. Thanks.

ProXR is from our Industrial series. The Ethernet Modem is from our Enterprise series. This means they get two different profiles installed in the wireless modules. The only real difference is Enterprise has Encryption enabled and industrial does not. This is why it needs to be noted in the order to disable encryption on the Ethernet modem.

It might be a safe bet to go ahead and order this board just in case you should need to change settings in the wireless modules in the future as well: