Controlling a floating point valve


Is there a way to control a floating point valve?
If you know the stroke time of the valve from closed to open. Say closed is zero seconds and 100% is 120 seconds

So if a immersion temp sensor was in the water pipe and you wanted to control the temp in a loop could you use a DO to open the valve for X seconds and look at temp and if it did not reach control set-point open the valve more (x more seconds). Almost a poor mans loop PID loop

If temp is above set-point set HIGH on GPIO x pin for 30 seconds then switch to low volts. wait 2 min and if temp is below set-point open valve more for x seconds. When it gets below set-point command the valve back to closed, I guess you could just run the do to close CCW or CW depending on how it was setup to force the valve closed.

Could I pull this off on Cayenne, is there a timer section that we could use to track the time intervals?


My idea to solve this is I hope we get a little python sandpit to pass variables to and from Cayenne and then people could build up little ‘solvers’ or solutions. This would open up the system so much more for me.

Could things like this be solved in a mini python ? Build equation blocks then solve various data also flying about in the Pi ? This would enable some real horsepower and a range of number formats (bit, polarity and float, Math)

Suggestion anyway…

~ Andrew


So yeah, as @picaxe mentioned, we’re looking to give Cayenne users the ability to customize the platform to fit whatever use case. This way, we empower you as the user to be creative with Cayenne.

If you’re interested, we’ll be discussing how to best achieve this for the Community, here: Online Meetup - 03/24/16 12pm - 1pm PDT


I am particularly interested in pyserial etc for getting variables IN and OUT the Tx Rx line of tty AMA0. This is shoe string technology but brilliant for a range of devices and micro’s such as the 8 pin complete micro platform. You only need 4 wires. The chip is already set up to do quite advanced serial coms. There are quite a few other low tech serial applications as well like GPS, I Use a local radio net / mesh on 433MHz to do a lot of ‘wild’ life and enviro monitoring. The remote devices can then be remote + uAmp powered with data streaming in over budget devices in the 433MHz band into the Pi tty AMA0. At the moment all I can do is watch minicom on ssh which is a little bit primitive. I am looking at alternative methods and have students making IoT type servers and things from scratch but the potential of Cayenne features + ‘user’ variable data would be huge. A general py sandbox on the Pi would suit me best. How about at least somehow bring in say multi channel CSV formatted variables ? Select baudrate and let rip etc…
~ Andrew