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Industrial PLC Electrical System

N

Naruto

Well Known Member
Hi guys,

I am a industrial programmer by trade and I am considering using a industrial PLC with a touch screen PC based HMI for my RV electrical system. I would like to know what others think if I should bother researching this for use in my RV. For those that do not know what a PLC is, it is a programmable logic controller used in industrial applications that are used to control machinery. A plc is composed of a processor, input and output modules that take field signals from devices like switches, transmitter and transducers to operate things like valves, motors and actuators. http://en.wikipedia.org/wiki/Programmable_logic_controller You can also take analog signals for indication displayed on the HMI (human machine interface). I figure I can take all the signals from flow meters, temp signals, RPM, practically any device that is a electrical signal into the PLC and program what ever I need to and control and monitor my electrical system. The HMI would be a 6 or 10 inch touchscreen pc based display with intouch software for the graphics interface to monitor and control my electrical system.

I use the graphics software for work so I would not have to shell out a bunch of cash for the HMI software and just purchase the PLC hardware and touch screen. The link is a brochure of the graphics package I plan to use so you can see the quality of the icons.

http://www.wonderware.com/downloads/inTouchBrochure.pdf

I would purchase the PLC hardware for Automation direct or similar vendor since their pretty cheap.

http://web3.automationdirect.com/adc/Shopping/Catalog/PLC_Hardware

HMI screen vendor.

http://www.superlogics.com/industrial-computers/panel-pc-computer/35.htm

My main concern is should I rely on a pc based HMI with touchscreen interface and PLC for my entire electrical system because if I loose power, then I am pretty much screwed without a screen to turn on switches and monitor gauges or readings from the screen.
 
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MCA said:
Dan,

We've designed a system for experimental aircraft that has this functionality, and more. www.verticalpower.com . You can wire backups to get power to critical systems in case of a failure.. details in the installation manual on the site.

You might also look at Al Wick's do-it-yourself system that he's been working on for a while.

http://www.maddyhome.com/canardpages/pages/alwick/index_files/Page575.htm
Click to expand...

Marc,

Thanks for the links. It looks like Al is also using wonderware but he must be using an older HMI version since version 10 is vista compatible and the graphics are 100 times better. I actually looked into your product and thought about purchasing it but figured I could do the same thing myself since I design and program control systems for a living for power plant, oil refineries and chemical plants. My company already pays for the development software for both the HMI and PLC and I just need to get the hardware and runtime license. My company typically use Allen Bradley PLC's but the automation direct will work fine for a 10th of the price.

I think your product is great and if I had more funds I would of bought yours but I'm too cheap :D. I need to save for that engine :eek:. BTW, if you don't mind me asking, did you guys develop your own HMI software or are you guys using a third party development software?
 
I thought about doing this too

These are my opinions. I am not an avionics engineer, and all of my data is totally worthless to anyone reading this. (Do I have that right for the US litigation waivers?)

I've worked industrial automation for a system integrator for 18 years, and am building an RV-8A.

I looked at verticalpower as well, and liked most of it, but the temperature range doesn't match the environment we have here in Saskatchewan, and I will not be able to afford heating a hangar.

Wonderware is a good package for the usual applications. I've used it (a bit, mostly the RSView flavours, Fix/Ifix and Cimplicity over the years).
The software won't matter. Display update rates for smoothness during flight should be faster than the usual 1s or so round trips in the industrial world.


I've used a bunch of different flavours of PLC, and you are likely to be unhappy with the weight vs performance requirements. Also, if I was doing this, I'd go with spring cage-clamp wiring rather than screw terminals due to the vibration environment. I'd be reluctant to use the usual card cage system for the PLCs. I'd need to consider stiffness of the surface that the chassis was mounted to (had a bad experience with a flexible mining machine) in order to extend chassis lifespan.

Any design that you come up with should have enough redundancy to allow for safe termination of the flight.

I've pretty much decided on GRT EFIS/EIS and a couple wraps of heat trace in circuit with the block heater to prevent the display freezing. I thought about the PLC possibilities, the need for mv thermocouple inputs ($$ I/O) etc, and put it away as taking too much space, too much weight, and too much money. Technically, it would be no problem to do, if I could ignore cost and weight.

My feeling is that unless you are getting the HMI HW and SW package for pretty darn cheap, you will be very hard pressed to integrate the application for less cost and time than the dedicated hardware folks can do it.

Remember that you are your own support and upgrade system as well, and that has to be rolled into the total life-cycle cost for the system. If you roll your own, you are also responsible for considering all of the failure modes, and finding a way to test them.

PM me if you want to go into more detail about this.
 
Howard,

Lots of great info and food for thought. I am still quite a while before I actually need to run any wire but have been thinking about the PLC & HMI system for a while. Most of the Dev software I get for free from work and can borrow the PLC and I/O modules also from work that are lying around, wink, wink :cool:. I think my out of pocket cost would really be the runtime license and the PC based touch panel. We use Allen Bradley compactlogix, Ethernet PLC's that are rackless, where the I/O modules snap together but I may consider the automation direct plc hardware if I don't have any extra AB hardware laying around at work when I need them. My flight bag with gear weighs 5 time more than my PLC would, so I'm not too worried about weight. BTW, I hate the AB rsview HMI package :p. I also have concerns about the screws possible loosening up due to vibration on the I/O modules.

In reality, I am considering this because I like the idea of simplified wiring to a single box and I can get most everything I need from work, but If I had to buy everything, It should cost no more than a couple thousand for a homebuilt electrical system glass panel, minus the actual programing work.
 
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Depends on "Why"....

It sounds to me like you have all the necessary background and equipment to build a system the way you are describing it, and if the reason that you are building is to exercise your creative energies and talents, then I'd say...why not? However, with that question comes a fairly standard answer....becasue you have no idea what kind of problems you might run into between conceptual design and finished system, and those problems could overshadow your entire airplane project.

When people want to do a lot of "out of the box" design work on their RV's, I suggest that you make sure you know why you're building. If your intent is to tinker and be creative, then pursue whatever you like and enjoy. But if your intent is to have a reliable, trouble-free flying airplane in a reasonable length of time, it is very hard to beat the tried-and-true light airplane systems that have millions of flight hours and decades of development behind them. My airplane is a heavily redundant IFR machine, with two alternators and a back-up battery in addition to the main battery - but the electrical system is actually very simple. It has three busses - but that just means three chunks of wire which can be joined or separated with a switch. It's really not complex at all - just electrician stuff. The less parts you have, the less parts you have to fail.

I never discourage innovation and creativity - that is, after all, what has brought us the airplanes we have today - but make sure that you understand the potential costs of that pursuit., There are many, many complex and innovative uncompleted homebuilts gathering dust in garages, because folks couldn't work the bugs out. The vibration and temperature environment alone can be a killer for electronics, and thousands of hours of testing and tweaking have gone into systems that are for sale (like VP's for instance).

I doubt that I personally would pursue a processor-controlled electrical system, but that is my choice for my own purposes. As long as people go into projects like this with their eyes wide open for the potential difficulties, who is anyone to tell them not to pursue their ideas?

Paul
 
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PLC in aircraft

After working in the Avionics and A and P field for 30 years I went back to school to study PLCs. I discovered that an autopilot system is nothing but a form of a PLC. They all have a computer and look at ones and zeros. The advantage's of rolling your own is you can tweak it to meet your needs, make whatever changes you want and change it back if needed. You will need to handle a lot of analog signals which will need a lot of modules and electrical noise issues to handle.

I am looking for a job in field service working with PLCs. Please let me know if you know of any.

Good luck in what you decide.
 
mike crowe said:
After working in the Avionics and A and P field for 30 years I went back to school to study PLCs. I discovered that an autopilot system is nothing but a form of a PLC. They all have a computer and look at ones and zeros. The advantage's of rolling your own is you can tweak it to meet your needs, make whatever changes you want and change it back if needed. You will need to handle a lot of analog signals which will need a lot of modules and electrical noise issues to handle.

I am looking for a job in field service working with PLCs. Please let me know if you know of any.

Good luck in what you decide.
Click to expand...

Mike,

I could not agree more. A PLC & HMI combo really does have limitless possibilities. I like the idea that I can take a switch from my stick and wire it as a digital input to a input module on the PLC, and program it to activate the flaps. I could program a safety feature that will only allow the flaps to be operated only at the appropriate airspeed where I would not have to worry about accidentally pushing the stick switch at higher air speed and having the flap get damaged. I could also program several alarms to warm me of potential problems.

I like wonderware new graphic package where it look extremely attractive and its windows vista compatible to boot.

SymbolLibrarypage4.jpg


InTouch10Leapspage2.jpg


I have not put that much thought into this yet since I am still far from needing a electrical system but my basic architecture would be a panel mounted touchscreen PC loaded with windows vista and wonderware 10 HMI software package, connected to the PLC (Allen Bradley or Automation Direct) via Ethernet. My communications from HMI to PLC would be either a DA server from wonderware or a OPC server from the PLC manufacture I choose. I will need to research the required I/O since I don't know what analog signals aviation transducers put out in the aviation market. If I want to keep my electrical control of the plane to a more traditional electrical system, I can just use the HMI as indication only and develop displays for flight instrumentation.

There is work out there for PLC programming all over the country, just look in career builders,you'll find a bunch.

When I get some time, I'll put together some flight instrumentation display screens just to see what it looks likes and post some pics.
 
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Not intending to suppress, but may save you some trouble

Ironflight said:
It sounds to me like you have all the necessary background and equipment to build a system the way you are describing it, and if the reason that you are building is to exercise your creative energies and talents, then I'd say...why not? However, with that question comes a fairly standard answer....becasue you have no idea what kind of problems you might run into between conceptual design and finished system, and those problems could overshadow your entire airplane project.

When people want to do a lot of "out of the box" design work on their RV's, I suggest that you make sure you know why you're building. If your intent is to tinker and be creative, then pursue whatever you like and enjoy. But if your intent is to have a reliable, trouble-free flying airplane in a reasonable length of time, it is very hard to beat the tried-and-true light airplane systems that have millions of flight hours and decades of development behind them. My airplane is a heavily redundant IFR machine, with two alternators and a back-up battery in addition to the main battery - but the electrical system is actually very simple. It has three busses - but that just means three chunks of wire which can be joined or separated with a switch. It's really not complex at all - just electrician stuff. The less parts you have, the less parts you have to fail.

I never discourage innovation and creativity - that is, after all, what has brought us the airplanes we have today - but make sure that you understand the potential costs of that pursuit., There are many, many complex and innovative uncompleted homebuilts gathering dust in garages, because folks couldn't work the bugs out. The vibration and temperature environment alone can be a killer for electronics, and thousands of hours of testing and tweaking have gone into systems that are for sale (like VP's for instance).

I doubt that I personally would pursue a processor-controlled electrical system, but that is my choice for my own purposes. As long as people go into projects like this with their eyes wide open for the potential difficulties, who is anyone to tell them not to pursue their ideas?

Paul
Click to expand...

Paul, it was not my intent to squash creativity. I was hoping to offer some of the conclusions that I, with a similar background and skill set, had reached after a bunch of preliminary engineering on the possibility. It was this process, starting based on my own industrial control and HMI experience, that led me to reject that option. I selected the GRT system. This was just before you got to be "RV of the week" and I saw an -8 with a similar panel layout to what I'd just arrived at.

Industrial equipment can be found that will handle the vibration and the temperature. That's no problem. Meeting those requirements and also not being very heavy is the problem.

Naruto, in my earlier post I mentioned problems with vibration and flexibility:
Specifically, it was related to the 1794 snap-together terminal bases on a base-plate that was too flexible. The compactlogix should have lots of jam for the size of the application here, but I'd be concerned about the I/O connections. The weight penalty for this equipment would be a heavy base plate.

I was planning to use pretty minimalist displays - black backgrounds and very little eye candy, no shading etc. to promote "take it in at a glance" and context-based switching. I really liked the 5 programmable buttons on the Panelmates, and was going to do something like that. I was going to hold off on the HMI hardware until the last moment, because it's all changing every 6 months or so.

I wouldn't use a touchscreen on this application, after flying around on a bumpy day. I'll probably follow something like Perihelion Design's switch guards, to allow someplace to anchor my hand while choosing which switch to operate.

Good luck with your design.
 
Naruto said:
I like the idea that I can take a switch from my stick and wire it as a digital input to a input module on the PLC, and program it to activate the flaps. I could program a safety feature that will only allow the flaps to be operated only at the appropriate airspeed where I would not have to worry about accidentally pushing the stick switch at higher air speed and having the flap get damaged.
Click to expand...

I think this is cool with lots of possibilities, but this is also where failure modes creep in. Your only original failure mode is to set out flaps at too high airspeed, but now you will have a whole bunch of failure modes like button failure, electrical failure, PLC failure, generator, software and so on that could actually set out the flap unintensionally at any airspeed.

In the Atec Zephyr I fly, the electric motor of the flap is linked with a small clutch. This clutch is adjusted so that the friction forces are too low to extend the flap when the airspeed is too high. The accuracy of this could be higher, and it needs to be adjusted from time to time, but the only failure mode of any remotely critical nature is that the clutch could be too loose and the flaps will not extend.
 
Naruto said:
BTW, if you don't mind me asking, did you guys develop your own HMI software or are you guys using a third party development software?
Click to expand...

Dan, we developed everything ourself for this specific application. The display uses a modified Linux and the other boxes operate in real time and don't have an OS. It's long way from cobbling some stuff together to making a production system you feel comfortable selling to others. But it can be an interesting project for those with the background in this area. And I believe, in due time, that solid-state switching will be the de-facto standard, just as EFIS and GPS is replacing steam gauges and VORs. It's already happening in many other industries.

There's a lot to consider, as you can imagine... the most important thing is the safety aspect as it applies to the aviation environment. Vibration ,temp, backups, specialized functions, etc. For example, the trim, flaps, and starter circuits are designed so that multiple things have to happen internally (to put it simply) to make those functions work, to avoid them operating when they shouldn't. But, once you go digital, the possibilities are endless.
 
Dan,

I was thinking some more about how you could do this and make it a manageable project. My suggestion is to install a traditional "backbone" wiring system, so that the master switch, field and starter switches are conventionally wired. Same with trim and flaps. Then the rest can be controlled by the PLC and they are simply on/off switches and discrete inputs. A touch screen would be a simple way to control these. You could wire backups as we've defined in our installation manual - see "method B." That'll get you going, then you can add more features with software and ways to switch devices on and off later as you have time.

Also look up "GlassPanel" group on Yahoo groups. These guys are into "built-it-yourself" EFIS and plc projects.
 
MCA said:
Dan,

I was thinking some more about how you could do this and make it a manageable project. My suggestion is to install a traditional "backbone" wiring system, so that the master switch, field and starter switches are conventionally wired. Same with trim and flaps. Then the rest can be controlled by the PLC and they are simply on/off switches and discrete inputs. A touch screen would be a simple way to control these. You could wire backups as we've defined in our installation manual - see "method B." That'll get you going, then you can add more features with software and ways to switch devices on and off later as you have time.

Also look up "GlassPanel" group on Yahoo groups. These guys are into "built-it-yourself" EFIS and plc projects.
Click to expand...

I agree, that the master switch, field and starter switches, trim and flaps should remain conventionally wired. My main purpose for the HMI, PLC combo would be for flight instrumentation monitoring (engine RPM, manifold pressure, fuel level, oil temp...ect), alarm annunciation, fuel computer and switching non-critical devices on and off using the touch screen. This will eliminate the unsightly row of physical toggle switches, some instrument gauges and open up more panel space for other things. Later if I want more automation, I could add things as I think of them to reduce pilot work load. This would be a project mainly to see the feasibility of using a PLC for aviation. I do not intend to make this a commercial product since I don't need the liability hassles. I personally like all the glass panels already out in the market but for some reason, the eye candy (graphics) just aren't too appealing and are pretty expensive. Computers displays have advance quite a bit and HMI packages are takeing advantage of higher resolution displays. Thanks for everyones input and I am always available to throw ideas around.
 
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Well, I finally got some time to build a screen for a engine monitor. I will spent a lot more time on it when I get closer to doing my electrical system.

Sample.jpg
 
Here are some default gauges, buttons, switches, ect. that can be used to operate different aircraft systems through a PLC and HMI touchscreen. The HMI software also comes with the ability to make you own graphics if your so inclined to do so.

2.jpg


1.jpg


3.jpg
 
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