Automated Greenhouse - Please Critique

[djkswiss]

Hi,

Please review and critique my plans noted below. While reviewing and critiquing please keep in mind that this will be my personal greenhouse, however the end goal is to implement the same 1 wire technologies into multiple greenhouses in the next 10 - 15 years. Is 1-wire going away in the near future... it almost seems like it is at its end of life... if so what is a suitable replacement technology?

My current plan is to build a detached passive solar greenhouse and utilize 1 wire technology to monitor and control certain aspects of the greenhouse.
1-Wire devices to be used:

• Soil moisture meters
• Humidity Sensors
• Temp Sensors
• Solar sensors
• 8 Channel I/O Relay (To control: SCHS, subterranean cooling and heating system) you can read more about schs by googling "subterranean heating and cooling system"., shade cloths, watering system)

The above devices will be controlled via the DS80C400. This device has Full TCP/IP Stack and a JVM with 1 wire capabilities and a serial and Ethernet connection. The code will be jsp with ajax calls to servlets to control/read the 1-wire devices.


A couple of questions I would like addressed.

1. Is 1-wire technology going away? Will I have a hard time finding the above mentioned devices?
2. The greenhouse will be about 75 ft from the house this leaves me with a few options for the location of the DS80C400

A. Run a 1-wire cable to the greenhouse and have a booster with the DS80C400 inside my home, not sure if boosters exist for 1-wire and I am thinking I am asking for trouble connecting devices that far away.​

B. Run a ethernet cable and power to the greenhouse and have the DS80C400 installed inside of the greenhouse.​

3. The 8 Channel Relay does not have high enough amperage to drive the blower motor for my SCHS. I plan on driving a larger relay with the output from the 8 Channel relay. Does this make sense to people with electrical knowledge?


Thanks for reading!

 

[Michael McSharry]

Run cat 5 to the greenhouse. Gives you much more flexibiltiy and your 1-wire will also be more stable with shorter lengths.
For moisture sensing I have been very happy with Vegitronix that has a analog interface. I had no luck with gypsum type probes and 1-wire. I use WebControl to interface the Vegitronix. I use temp sensors to assess solar by taking the difference between a sensor that is exposed to the sun and one that is in the shade. I have had 3 1-wire solar sensors and all three have failed within a year. The WebControl also supports humidty and temp sensors and had 8 channel discrete output. Likely you could use the WebControl for your logic as well, but not familiar enought to know the complexity of your algorithms.

 

[ericvic]

1. Dallas has been discontinuing some of their less popular 1-Wire chips but I don't see them discontinuing the temperature chip any time soon. As for other devices we have started using our own custom 1-Wire slaves so they will be available.

2. Like Michael said if you run CAT5 to the greenhouse then you will be set either way you decide to go. 75 feet is not too long for a 1-Wire run, we have customers that have runs much longer than that on systems that are working fine.

3. Using the 8 Channel I/O to drive a larger relay will work just fine.

Eric

 

[djkswiss]

Run cat 5 to the greenhouse.  Gives you much more flexibiltiy and your 1-wire will also be more stable with shorter lengths.
For moisture sensing I have been very happy with Vegitronix that has a analog interface.  I had no luck with gypsum type probes and 1-wire.  I use WebControl to interface the Vegitronix.  I use temp sensors to assess solar by taking the difference between a sensor that is exposed to the sun and one that is in the shade.  I have had 3 1-wire solar sensors and all three have failed within a year.  The WebControl also supports humidty and temp sensors and had 8 channel discrete output.  Likely you could use the WebControl for your logic as well, but not familiar enought to know the complexity of your algorithms.

Hi Mike,What kind of problems did you have with the 1-wire soil moisture sensors? I'm not sure how I would interface the analog device with 1-wire, however I am sure it would be possible. I would rather not stray in the direction of creating my own circuits as I already have a lot on my plate to accomplish(assembling greenhouse, writing code for greenhouse). I'd rather use the soil moisture meter available from hobby boards.

 

[Michael McSharry]

A resonable evaluation is provided at [url="http://www.sowacs.com/sensors/gypsum.html"]http://www.sowacs.com/sensors/gypsum.html[/url] In my case the problems are more basic. If I placed the sensor sufficiently deep I would never change over several days. If I placed it closer to the surface then the sensor circuity responded more to heat/cool cycles associated with daylight than it did to moisture content. There are some graphs that were posted on cocoontech several years ago.

Eric did sell a HVAC monitor in the past that had 4 A/D input (DS2450) channels for 1-wire. I'm not certain if any of his current products provide a general purpose A/D input or could be repurposed for this use.

Whatever you do make certain you electronics have the proper conditioning for the environment. Unconditioned spaces tend to be hard on connections and condensation will occur so you need coatings.

 

[djkswiss]

A resonable evaluation is provided at http://www.sowacs.co...ors/gypsum.html In my case the problems are more basic. If I placed the sensor sufficiently deep I would never change over several days. If I placed it closer to the surface then the sensor circuity responded more to heat/cool cycles associated with daylight than it did to moisture content. There are some graphs that were posted on cocoontech several years ago.

Eric did sell a HVAC monitor in the past that had 4 A/D input (DS2450) channels for 1-wire. I'm not certain if any of his current products provide a general purpose A/D input or could be repurposed for this use.

Whatever you do make certain you electronics have the proper conditioning for the environment. Unconditioned spaces tend to be hard on connections and condensation will occur so you need coatings.

The 8 channel relay also has inputs. However it seems that it only measures between 5v and 30v and the vegitronix moisture meter outputs up to 3v. Any suggestions?

 

[Michael McSharry]

I think Eric would have the best opinion as to what device could be put into play as a 0 to 5 (3VDC) A/D. He has several DS2438 variants and it seems like one of those could be used. For example replace the Honeywell humidity sensor with a Vegitronix probe in his Humidty or combo sensor.

 

[FrankMc]

Run cat 5 to the greenhouse. Gives you much more flexibiltiy and your 1-wire will also be more stable with shorter lengths.
For moisture sensing I have been very happy with Vegitronix that has a analog interface. I had no luck with gypsum type probes and 1-wire. I use WebControl to interface the Vegitronix. I use temp sensors to assess solar by taking the difference between a sensor that is exposed to the sun and one that is in the shade. I have had 3 1-wire solar sensors and all three have failed within a year. The WebControl also supports humidty and temp sensors and had 8 channel discrete output. Likely you could use the WebControl for your logic as well, but not familiar enought to know the complexity of your algorithms.

Hi Michael

I installed several of the Vegetronix sensors in my vegie patch and while they worked fine in test pots i found that when installed in my vegie garden it would take days before any change in moisture level...These were the VG400 sensors...Which one were you using ??
Thanks
Frank

 

[Michael McSharry]

I believe I am using the same model Vegetronix sensor. When installed in an environment were the soil only looses surface moisture the sensor performs poorly. When installed in the environment were the sunlight truely dries out the soil they work quite well. This would be consistent with your test case where the total environment that the probe was sensing lost moisture. Summertime in the desert I can see hourly changes. In the winter I see no change. Without the strong sunlight the moisture content in the soil is at equillibrum.

 

[FrankMc]

Thanks Michael

Frank