July 19, 2013 at 5:34 am #22543
I’ve got my OpenSprinkler PI running on 11 zones (sequentially). For some reason, the regular programs aren’t running. So while I figure that out, I just entered a run once program. IF that manual program has more than one zone with non-zero time, the Pi reboots. If it has 1, it runs fine to completion. Any ideas?July 19, 2013 at 5:59 pm #24877
I’m pretty sure there’s a very dangerous bug in the manual program that causes all selected valves to turn on at some point. Because I’ve blown 1 transformer so far.July 20, 2013 at 11:39 am #24878
In manual mode, ‘all selected valves’ will surely all turn on, because in manual mode you click on / select each valve to turn it on. So I assume ‘all selected valves’ mean you’ve manually selected all valves, and that should turn on all valves.
In any case, what kind of transformer do you have? Normally if the transformer is overloaded (say because it can’t drive more than 1 valve), the voltage will drop instantly, causing the controller to restart, and hence release the valves. The only issue I can think of is if you have a persistent shorting somewhere, and hence the transformer will be damaged. I think it’s important to perform further investigation before arriving at a conclusion.July 20, 2013 at 8:30 pm #24879
I’m not in manual mode, I meant “run once program” mode. I have an alarm transformer – 24v 40vaJuly 20, 2013 at 8:31 pm #24880
Before I had a sprinkler transformer – 300 ma, which blew for sure when I ran a run once program with multiple zones specified. Plus we saw them all turn on, so that was pretty good evidence.July 20, 2013 at 8:41 pm #24881
Well, 300mA is not sufficient to run more than 1 valve. Each valve draws about 180mA to 200mA current (and also the inrush current can go as high as 500mA to 600mA). Plus if you are powering RPi from OSPi (using the 3-pin cable), that will require another 100 to 150mA current. So with 300mA transformer, it’s barely enough to drive one valve plus RPi. As the OSPi user manual describes, the transformer should be rated at least 500mA.July 20, 2013 at 8:45 pm #24882
But I didn’t ask to turn on more than 1 valve. I asked to run a run once program, which should respect the sequential setting that regular programs do. Now, additionally when I put in the 40va transformer, although it didn’t burn, two very bad things happened given that I’m not at the home. 1) Interval started complaining that it couldn’t find data/meta.txt for some reason, and 2) sshd stopped working. So basically I was shut out of the system, had no way to find out the sprinkler status, and had to find somebody to go there and install a regular timer because the OpenSprinkler PI couldn’t be trusted.July 20, 2013 at 8:48 pm #24883
Out of curiosity, why not use relays instead of triacs? The relays could be wired such that it’s impossible to turn on more than one zone (by daisy chaining) while the triacs leave the possibility of doing very bad things (like this).July 20, 2013 at 9:03 pm #24884
Well dj some people do run more than one zone at a time so the hardware should be designed to accept any command sent to it from the software. But you’re right there is a very bad bug in the run once programming. I tried running it (luckily I was standing next to the rPi and was able to unplug it before anything could be damaged), and all the zones started flickering on and off like crazy. It started making the transformer buzz and physically vibrate. I’m using a rainbird brand transformer.
I had my rPi setup to use a 8 channel relay board when it did this so using relays doesn’t fix the problem. And yes, even while using the opensprinkler pi board, running the run once program will cause all of the zones to flicker on and off the same way.July 20, 2013 at 9:12 pm #24885
Frankly I don’t think the problem is with triacs. With relays you could damage your transformer in the same way. In fact, triacs at least have internal limit on the maximum current (e.g. 800mA), while relays have literally no limit on the allowed current, so you can potentially run a much higher current through it, causing ever worse damage. Also, if you can daisy chain relays you can also daisy chain triacs. In practice, unless if we are talking about power-line devices, for low-voltage devices I would always prefer traics: they are more much compact, cheaper, and have faster switching speed.
The issue you have encountered is rather unusual. As I said, typically when the transformer is overloaded, the voltage will drop rapidly, causing the controller to reset and release all valves. Actually, now I think about it: are you powering RPi through OSPi, or do you power RPi through a USB cable? In the latter case, when the transformer is overloaded, RPi will still keep the triac open (since it’s powered separately), and I can imagine this would damage the transformer.
For flexibility, I can’t put a hardware limit to restrict the number of open stations. Many users have a master station, which should be turned on concurrently with other stations. Also, some users use OpenSprinkler to control not only sprinkler valves, but also landscape lighting. They certainly don’t want lighting to be serialized. So I can’t put a hardware limit for one station at a time. This has to be implemented as a software limit. OSPi’s interval_program is currently designed to run stations sequentially only. But it may have a bug that causes more than 1 stations to open at the same time. I will communicate with Dan about the issue.July 20, 2013 at 9:24 pm #24886
The latest OSPi program that Dan just released today fixed the issues I was having with the run once program. Thanks for yalls awesome support!July 20, 2013 at 10:04 pm #24887
With relays, I could easily wire them in series so that when one goes on, any relay AFTER it gets no current and thus can’t go on.July 21, 2013 at 12:49 am #24888
Right its possible, but most people dont want a set up like that because they either turn on multiple zones at once or have a master with other zones.
But either way, update your program to the newest version on the github and it’ll fix your problems.July 21, 2013 at 5:01 am #24889
Great, will do. But doesn’t the existing interval program now force single zone at a time? I’d like “n zones at a time” actually. Starting to think maybe Interval isn’t for me and I’ll have to get out my node.js weaponry.
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