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Old 08-09-2013, 03:59 PM   #21
malador
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Haha... I'll agree with half of that, you absolutely can't pay more. However, I'm sort of a Rockwell fanboy. I've got a couple of L71 processors on my desk at work right now and they are a pleasure to work with. So please enlighten me, what is better?
One thing Rockwell has going for them is that they support their products for a LONG time. Personally I don't think there is something better than the 5000's for the money. (disclaimer I also have very limited experience with other brands) When it comes to smaller items like patch cables,terminal blocks and power supplies, I feel there are lot better ways to spend your money. Unless you just like having AB stamped on everything in your panels.
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Old 09-02-2013, 07:16 PM   #22
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Im a commercial HVAC tech but most of my experience with automation comes from Johnson Controls DDC. I also just generally like messing with electronics and have a bit of experience with arduino. i had planned to make an arduino based automated brew rig but since i now have a braumeister, i dont really see the need. until i want to upgrade the capacity of my system and identify the short comings of the BM to improve on a new system design, ill probably stick to what i have.

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Old 09-04-2013, 06:03 PM   #23
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I'm a controls engineer for a consulting company. I fortunately get to do a lot of work for one of the big brewers (how can it be work if I get to deal with beer every day?) I've touched just about every brand of PLC over the years, but have the most experience with Allen-Bradley. My first system used a couple smart relays (A-B Pico) with stand-alone PIDs. However, several years ago I won a starter kit as a door prize from a local distributor that included a Siemens S7-200 PLC. Over the years, I've gotten expansion modules (thermocouple & RTD input & DC output) along with an HMI via eBay to complete my system. My system keeps evolving so that the latest version is all electric with two pumps, two solenoids valves and uses my CFC for both mashing and cooling. Still some bugs to work out, but that's where the fun is...

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Old 10-14-2013, 07:59 PM   #24
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Wow all you guys seem to have a lot of experience in PLCs. But one thing that always puzzles me is what is the benifit of going for a PLC control (for our homebreweries, etc) over a microcontroller? To me the PLC seem more restrictive in both hardware and programing (but I also have no real knowledge apart from "they are programed in ladder logic, which is kind of like relay logic").
After look for the answer myself for a while all I could come up with is that in an industrial installation where they end product would likely be maintained by the site maintenacne electricians that PLC/Ladder logic has become the default standard - i.e. most of them know how to deal with ladder logic since it follows a similar methology of relay logic.
So is the reason you guys are using these because it is easier for others (or yourself since you have no learning curve to deal with) to deal with a PLC rather than lines and lines of code?

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Old 10-14-2013, 08:04 PM   #25
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Wow all you guys seem to have a lot of experience in PLCs. But one thing that always puzzles me is what is the benifit of going for a PLC control (for our homebreweries, etc) over a microcontroller? To me the PLC seem more restrictive in both hardware and programing (but I also have no real knowledge apart from "they are programed in ladder logic, which is kind of like relay logic").
After look for the answer myself for a while all I could come up with is that in an industrial installation where they end product would likely be maintained by the site maintenacne electricians that PLC/Ladder logic has become the default standard - i.e. most of them know how to deal with ladder logic since it follows a similar methology of relay logic.
So is the reason you guys are using these because it is easier for others (or yourself since you have no learning curve to deal with) to deal with a PLC rather than lines and lines of code?
I don't think i know what you mean by microcontroller. I use that term for small PLCs. I don't think it's fair to say that PLCs are restrictive. Can you give an example? I use a plc because i understand the logic, and there are some great inexpensive options out there.
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Old 10-14-2013, 10:52 PM   #26
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I don't think i know what you mean by microcontroller. I use that term for small PLCs. I don't think it's fair to say that PLCs are restrictive. Can you give an example? I use a plc because i understand the logic, and there are some great inexpensive options out there.
Sorry, I mean microcontroller as in the likes of Arduino (I realise that a PLC is a microcontroller ), I'm not trying to argue that nobody should be using a PLC for homebrewing but I want to understand the benifits/restrictions of using them (both for DIY use and industrial). The biggest benifit (and kind of the only definitive one I could find from the internet) was that PLCs are so common place now and built around a language that those maintaning the plants inherently understand due to its link to physical relay logic that it is best suited for the specific situation. For DIY/homebrewing I just don't see that benifit transfering so that anyone that does not have a PLC background would benifit from using a PLC.
What I meant by restrictive was, (hardware) for IO each point is dedicated to a digital input or a digital output or an analogue input... which I would see ending up with spare IO which could mean you had to buy more IO blocks than if you could switch between IO types. Another question is what type of temperature sensors can you use?
(software, and I am likely completely wrong here ) from the small amount of ladder logic I have seen it looked like mostly "if" type arangments. I guess this is not an issue for the core function of the PLC which is basically "if something happens do something about it", but what I have seen is if you want to add a touchscreen or something you need to purchase a compatable one that the "screen" is controlled by itself and is only sending requests to do stuff to the PLC.
I guess my question would be answered with the answer to another question, If I want to build a controller that will control the following, what would it cost:
8 actuated valves
5 temperature inputs
4 PWM outputs (heat elements / pumps)
1 flowrate inputs
1 touchscreen HMI
Both of these should be able to be done either with an Arduino or PLC, but what would the cost be?
For Arduino I would estimate for the controls side only, i.e. not including the actual valves, sensors, controlled equipment (roughly):
Controller - $50 (Arduino Due)
8 Digital outputs (valves) - $30 (relay board)
5 Digital inputs (temp) - $10 (misc costs)
1 Digital inputs (flow) - $10 (misc costs)
4 PWM outputs (heat elements / pumps) - $10 (misc costs)
1 amount of flowrate inputs - $10 (misc costs)
1 touchscreen HMI - $40 (3.2" touchscreen - small I know )
Total = $160
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Old 10-15-2013, 04:03 AM   #27
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The out of the box PLC's can be useful in brewing but the software lacks the flexibility to do much more than simple process control. Beyond that and you are into roll your own software application to bring all the rest of the functionality into play.
While the Atmel processors used in the Arduino series hobby boards are handy, they are limited in what can be expected of them. For basic Brutus style single infusion systems as well as basic RIMS and HERMS systems, the Arduino platform can be made to work reasonably well.
When you get beyond the basic systems and need analog outputs for flow control you need more robust hardware. One approach is to use PLC type IO hardware like I have, and write an application to make it work, or design and build IO boards that connect to a tablet or laptop running a control application.
For me the Phase 2 system was test of hardware and software, Phase 3 project is to bring the same control functions to custom IO boards that have same functions as Opto 22 hardware, with tablet sized foot print.

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Old 10-15-2013, 08:14 PM   #28
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The out of the box PLC's can be useful in brewing but the software lacks the flexibility to do much more than simple process control. Beyond that and you are into roll your own software application to bring all the rest of the functionality into play.
While the Atmel processors used in the Arduino series hobby boards are handy, they are limited in what can be expected of them. For basic Brutus style single infusion systems as well as basic RIMS and HERMS systems, the Arduino platform can be made to work reasonably well.
When you get beyond the basic systems and need analog outputs for flow control you need more robust hardware. One approach is to use PLC type IO hardware like I have, and write an application to make it work, or design and build IO boards that connect to a tablet or laptop running a control application.
For me the Phase 2 system was test of hardware and software, Phase 3 project is to bring the same control functions to custom IO boards that have same functions as Opto 22 hardware, with tablet sized foot print.
Could one not PWM the typical PSC motors that are used on homebrew size pumps? This could be done with an Arduino, couldn't it?
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Old 10-16-2013, 03:56 AM   #29
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Using PWM control with the small home brew type pumps would be quite a challenge because the relation to output vs. RPM is not a linear function. There is a term for the condition called "pump output curve", which in simple terms means as flow begins small changes in pressure create big changes in flow, as flow reaches maximum the pressure effects diminish and flow is relatively stable. For the .15 - 1 GPM range trying to maintain a flow by adjusting RPM would be quite an adventure. That is why a valve is easier to control flow with when pump is operated at stable operating point on curve.
For the Brewtroller platform, I would suggest the use of 2 digital outputs and a slow actuator to get what is known as floating control. This method has been around for over 60 years in commercial controls, and is still supported by many valve actuator manufacturers. The cheaper 12V ball valves and actuators are probably too fast to use as the normal time from stop to stop is 90 seconds for floating control actuators. If a slower actuator can be obtained then you would be set, fast ones for flow switching, slow ones for flow control.
Software control scheme would be to pulse output to drive actuator until process feed back indicates correct flow, no need for a home position as control will drive in correct direction at start.
For a PID control loop, PWM would be the ticket, the closer to set point the lower the "on" duration time of the output pulse.

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Old 10-17-2013, 07:08 PM   #30
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I must say this has been one heck of a great read so far.

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