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Today's Topics:
1. Re: Controlling valves (David Smith)
2. Re: Controlling valves (Andrew)
3. Re: Controlling valves (Andrew)
4. Re: Controlling valves (Andrew)
----------------------------------------------------------------------
Message: 1
Date: Thu, 26 Sep 2013 15:31:07 +0100
From: David Smith <Dave.Smith@st.com>
To: <bristol@mailman.lug.org.uk>
Subject: Re: [bristol] Controlling valves
Message-ID: <5244452B.20804@st.com>
Content-Type: text/plain; charset="ISO-8859-1"
On 09/26/13 15:26, Andrew wrote:
> Happy to write some sofware, C or Java. I just had the idea there must
> be some templates around. Given that people are doing this all the time
> all over the world. I assume. In particular, I imagine that solenoid
> valve drivers, for instance, must have been done again and again.
Well, there's not much software to write for a "solenoid valve driver" -
they just operate from a GPIO pin, so you just need something that'll do
that. The main potential difficulty is in getting enough GPIO pins
(especially on a PC) and the hardware interfacing task of getting
suitable voltage and current capacity to drive the valve.
------------------------------
Message: 2
Date: Thu, 26 Sep 2013 15:31:33 +0100
From: Andrew <andrewsoltau@gmail.com>
To: Bristol and Bath Linux User Group <bristol@mailman.lug.org.uk>
Subject: Re: [bristol] Controlling valves
Message-ID: <52444545.8090807@1dtv.com>
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
On 26/09/13 15:17, David Smith wrote:
> On 09/26/13 14:40, Andrew wrote:
>> Hi All
>>
>> I have been asked to do a project which involves using the pc to turn on
>> and off some valves with reasonably accurate timing. I would be grateful
>> if someone could point me in the right direction. I have done some
>> googling but the subject seems to be massive and lots about robotics and
>> nothing terribly simple. Terribly simple is what I am after!
>>
>> Firstly, what sort of software does one use for this? And where do I get
>> the control valves - I assume I don't go to maplin, or is that the
>> simplest way? Pressures are quite low, 10 psi or so, and the pipes will
>> be quite small bore, like windscreen washer stuff. Might need to use a
>> passed volume sensor / flow meter / however one does that.
> I doubt you'd find that sort of stuff at Maplin. I'd start by doing
> some searching (try "miniature solenoid valve" as a starting point) and
> maybe look at RS.
Thanks
>> This would all get prototyped on a standard pc with Debian. The final
>> objective is a using a raspberry pi with simple go buttons to set off
>> different sequences of operations.
> Personally I'd be tempted to go for Arduino rather than a RPi. I'd say
> that the Pi is probably a little "heavyweight" for this application.
> The Arduino has its own custom software environment for doing exactly
> this sort of thing.
Aha. I had an idea there might be something like that about.
>
> As for how to do the control, it depends on what valves you get, what
> voltage/currents are needed to drive them, and what sort of switching
> frequency and longevity you need - for example, if you need a
> significant current and/or voltage, you might want to use relays, but if
> they're switching frequently and need to last for a long time (rather
> than this just being a demo project or something used occasionally) then
> you may need to go solid-state. Either way, it's unlikely you'd be able
> to drive the valve directly from the Arduino/RPi because the valve would
> require more power than the device can supply.
It is for a long term use; and reliability is an issue once it is up and
running. It's all very low key. Low pressures, not a lot of on and offs.
I assume relays would be ok.
Thanks for all that. Arduino looks perfect.
Andrew
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Message: 3
Date: Thu, 26 Sep 2013 15:36:10 +0100
From: Andrew <andrewsoltau@gmail.com>
To: Bristol and Bath Linux User Group <bristol@mailman.lug.org.uk>
Subject: Re: [bristol] Controlling valves
Message-ID: <5244465A.5000300@1dtv.com>
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
Hi David
On 26/09/13 15:21, david wrote:
> It depends on the scale, I am doing a lot of this commercially using
> Labview.
> That is a expensive National Instruments product.
Looking at their site this looks great.
> But some years ago they did give away a Linux version, which can still
> be downloaded from a German site. It is good and powerful, but has
> quite a learning curve.
That sounds ideal. But a bit of googling only turned up this forum post
which concluded there was nothing like that available:
http://forums.ni.com/t5/LabVIEW/from-where-can-i-donwload-labview-for-Ubuntu-10-04/td-p/1250354
> Labjack do some interface boxes with labview drivers for < ?100
That sounds just the job.
>
> However I would recommend starting on the Raspberry, looking at the
> home robotics shops, and use Python or any language you are happy with.
> David
Thanks
Any thoughts on pi vs arduino?
Andrew
>
>
> On 26/09/13 14:40, Andrew wrote:
>> Hi All
>>
>> I have been asked to do a project which involves using the pc to turn on
>> and off some valves with reasonably accurate timing. I would be grateful
>> if someone could point me in the right direction. I have done some
>> googling but the subject seems to be massive and lots about robotics and
>> nothing terribly simple. Terribly simple is what I am after!
>>
>> Firstly, what sort of software does one use for this? And where do I get
>> the control valves - I assume I don't go to maplin, or is that the
>> simplest way? Pressures are quite low, 10 psi or so, and the pipes will
>> be quite small bore, like windscreen washer stuff. Might need to use a
>> passed volume sensor / flow meter / however one does that.
>>
>> This would all get prototyped on a standard pc with Debian. The final
>> objective is a using a raspberry pi with simple go buttons to set off
>> different sequences of operations.
>>
>> Cheers
>>
>> Andrew
>>
>>
>>
>> _______________________________________________
>> Bristol mailing list
>> Bristol@mailman.lug.org.uk
>> https://mailman.lug.org.uk/mailman/listinfo/bristol
>>
>
>
> _______________________________________________
> Bristol mailing list
> Bristol@mailman.lug.org.uk
> https://mailman.lug.org.uk/mailman/listinfo/bristol
>
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Message: 4
Date: Thu, 26 Sep 2013 15:37:59 +0100
From: Andrew <andrewsoltau@gmail.com>
To: Bristol and Bath Linux User Group <bristol@mailman.lug.org.uk>
Subject: Re: [bristol] Controlling valves
Message-ID: <524446C7.8070505@1dtv.com>
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
On 26/09/13 15:31, David Smith wrote:
> On 09/26/13 15:26, Andrew wrote:
>> Happy to write some sofware, C or Java. I just had the idea there must
>> be some templates around. Given that people are doing this all the time
>> all over the world. I assume. In particular, I imagine that solenoid
>> valve drivers, for instance, must have been done again and again.
> Well, there's not much software to write for a "solenoid valve driver" -
> they just operate from a GPIO pin, so you just need something that'll do
> that. The main potential difficulty is in getting enough GPIO pins
> (especially on a PC) and the hardware interfacing task of getting
> suitable voltage and current capacity to drive the valve.
>
Ok. Thanks. My only experience of writing drivers was at low level for
some hot swap RAID boxes and it got ferociously complex very quickly!
Andrew
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