Wireless or radio I/O?


I have a SNAP PAC in my greenhouse and would like to have wireless or radio analog sensors placed throughout the structure. They may move over time between plants. I didn’t see any solutions on the site, but I assume someone must have wired up a wireless sensor solution. Suggestions? I assume I could wire in a relay station of some sort…


Quick question that will help us all brainstorm ideas…

What range are you needing? (Are they sensor to master, or do you need a mesh?)
What power options for the sensors are there? (ie, do they HAVE to be battery, or is there 12v, solar, 110vac, 240vac etc).
Lastly, what are the sensors sensing? Temperature? Humidity? Light? Water? Rain? Wind speed?



Hi Ben,
Range is at most 150’…sensor to master. Only real power option would be battery. Here are the two sensors I currently use…they measure water content, EC levels and temp in the plant medium…

I am hoping to find an option for Opto. I currently have the 10HS hard wired which means I have few options to relocate. The GS3 I have plugged into a datalogger which I have to disconnect and download periodically. I would love to have real time data I could pull through the PAC and dump into SQL via the datalink. Love that program by the way…


First up, a plug for Opto. We do make wifi brains, EB1-W and EB2-W. Our smallest rack is 4 modules, so that ends up a pretty small box when you throw in a 5v PSU. No question it would be quick and clean with (at the very least) these two sensors.
Having power at a few locations would make things work a LOT smoother… as Im sure you already know. But, you said you don’t have ready access to power at these locations, so that makes things a little tricky.

I’m not sure what sort of transmitter I’d go with. You have one sensor that outputs millivolts and the other serial data.
Also, the 10HS draws 12mA… that’s pretty solid… If you can get away with turn it off and only turning it on once every 30 minutes or so to take a reading, but then you are looking at having some local control.
If you cant do that, then you are looking at a good sized big battery, or swapping batteries pretty often.

The serial at .3mA and 25mA when sensing is a bit better, but then you have that pesky serial data to deal with (easy if its hooked into a SNAP-EBx-W).

Here are a few milivolt transmitters;
Cheap version; http://www.monnit.com/Products/Wireless-Sensors/Commercial-Coin-Cell/900-MHz/Wireless-Analog-Voltage-Sensors
Are you friendly with soldering irons and can home brew your own? http://www.makershed.com/products/wireless-sensor-node

Note, I have not used any of them, just been Googling and reading around…
The serial is a lot more problematic…
These guys were next to us in a booth at a trade show; http://gridconnect.com/usb-to-serial/wireless-serial.html
Don’t know anything about them (the guys seemed cool).

Anyway, you get the idea. Is there a transmitter that can do say 1 chan analog and 1 serial and use very little power? Lets know if you find one…
Also lets know what you end up figuring out. I am really interested in wireless stuff and Im sure others would be curious to know what you ended up running.


Thanks Ben. I am reviewing options. What Opto module(s) would be required to read the data from the GS3 mentioned above?


Since its just serial data, you could go into a PAC S, or an R controller.
If you have more than 1 sensor at any one location, then you will need to see how many serial ports are in use at the PAC S location.
In the case of the PAC R, you would need to add more SNAP-SCM-232 modules to the rack (Each module adds two serial ports).
If you are running EB’s, then the serial module is the only way to go as the EB does not have an onboard serial port (as the R’s and S’s do).

Your strategy would then open a comm handle to that serial port, receive the data and then massage it to what ever form you like.
From there, you could put it in a table, store it as a file, email it, send it to a data base… Lots of options.


hi guys
just an observation… the GS3 quotes: Serial TTL, 3.6 Volt Levels or SDI-12.

to use with a RS-232 compatible port, you’d probably need a converter (maxim 232 chip (used them, they’re awesome) or similar) to generate the required voltage levels. first hit on google: [URL=“http://www.bb-elec.com/Products/Serial-Connectivity/Serial-Converters/TTL-Converters.aspx”]http://www.bb-elec.com/Products/Serial-Connectivity/Serial-Converters/TTL-Converters.aspx

SDI-12 seems to be a 1-wire serial type connection. therefore the standard RS-232 modules and ports would not be compatible.

i hope this helps.



Great catch!!! Man, I’m kicking myself for missing that one!
I’m in the middle of RS232 level conversion hell at the moment with a skunk works project… Its using a 3.3 micro to mash out the serial data I need put into a PAC… Not haveing a lot of fun… Since its going to be a project that ends up on these forums (hopefully) I want to be able to steer people to a serial level converter that’s as close to plug and play as I can… Not easy…

Anyway, thanks a heap for posting!


hey ben,
hmm sounds very interesting. anything with a micro is always fun and games…
have you checked out things like this http://www.emartee.com/product/41777/. you need an external supply but i reckon a bit more delving you’d probably be able to find one that will use CD or something. saves the whole breadboard and soldering iron thing…


Just want to throw my two cents in here… another option is a wireless I/O radio setup. Checkout http://www.bannerengineering.com/en-IN/products/60/Wireless-I-O

I’ve had my distributor rep demo a set to me and they seem pretty versatile. I haven’t yet had the chance to hook it up to and Opto rack yet to put it through it’s paces though. We use other Banner products in our panel shop and have been fairly pleased with their quality and availability.