The other day I mentioned that the propagation systems had been completely finished, and I would like now to show you the finished product. This first picture is of the main screen of the operator interface panel, which shows 4 completely different temperature values since all 4 zones have now been completed. I also made the numerical font size a little bigger.
Photo below - I also used a piece of white marking board to create a door for the long shelf propagation system. Since it was very lightweight and had good light reflecting qualities on the side that was white, I just had to try it. Some small, bent nails are used to keep the bottom and sides in contact with the surface of the shelf, because it's very flimsy - which causes it to bow outward. To open the door, I just rotate each bent nail 180 degrees, then lift the door up. Once up, 2 more nails are used to keep it from falling back down. Very low tech stuff for this construction. I wish everything was this simple!
Photo below - I wanted to show you a closeup pic of one of the homemade temperature sensors. This is type J thermocouple wire, which will sense temperature at the point at which the 2 wires (which are comprised of 2 different metals) are connected. This is the millivolt signal that is sent back to the thermocouple input module of the PLC, and is representative of the temperature value that it is exposed to.
Since these were kinda difficult to see in the video the other day, I wanted to give you a better view of the cellpacks in place. Also, notice that the fluorescent bulb on the far side isn't burning. Due to pretty cold temperatures in the shed right now it takes several minutes to turn on, and is starting to get on my nerves a bit. I don't like it when my stuff doesn't work right, and this light is coming out! It'll be replaced with a couple of t8 fixtures that have electronic ballasts in them, because they have no problems starting under pretty cold conditions. Chalk one up for trial and error, because I wasted alot of time on this light. :-( If indoors, it would have have worked just fine......
I also changed the temperature setpoints for each zone in my plc program, because I found out that a range of 70-75 degrees was actually a little bit too high. 60-65 is more like it, and helps promote a stockier plant stem. In less than 3 weeks, we'll be starting seeds with the wet paper towel method - which is the quickest way for germination to happen, in my opinion.
The temperature trending is working also, and gives me historical measurements every 30 minutes, over a 24 hour period. This will provide valuable information for seeing what goes on inside the systems while I am away. I'll probably go out to the shed each morning before work, just to see if any problems were experienced throughout the night. This is gonna be pretty fun!
Take care, and happy gardening!