question to the industrial OEMs
testsubject
Posts: 4
Hi all,
I recently came across this site and am amazed at the propeller. I am thinking about using it in a project I am currently developing. My question goes out to the OEMs.
Why did you go with this particular device instead of using a PLC? I have worked in the packaging industry for 17 years and practically everyone uses PLCs from somebody (Automation·Direct, (my personal favorite), Allen Bradley, Seimens, etc.) How do you justify all the design time (like with the pingpong ball counter which appears to be a one-off). Also how did you convince your customers to go along with accepting that this device was in their machine and that there techs would·probably not be able to·modify it?
I hope no one here misunderstands. I am not trying to start a flame war. This is something that I have had to fight about when I tried to convince the owner to switch away from using PLCs. He would say·"the customers expect PLCs and they will not buy our product if there are not any in there." I could definitely see how this chip could easily control the simpler machines that we build. It would require designing a PC board that would handle (8-10) 24 VDC inputs and (6-8) 24 VDC outputs. This is the part that may be hard to justify when you only make 40-50 machines a year and the part you are replacing only costs $130.
Thanks in advance for your time.
Bob
I recently came across this site and am amazed at the propeller. I am thinking about using it in a project I am currently developing. My question goes out to the OEMs.
Why did you go with this particular device instead of using a PLC? I have worked in the packaging industry for 17 years and practically everyone uses PLCs from somebody (Automation·Direct, (my personal favorite), Allen Bradley, Seimens, etc.) How do you justify all the design time (like with the pingpong ball counter which appears to be a one-off). Also how did you convince your customers to go along with accepting that this device was in their machine and that there techs would·probably not be able to·modify it?
I hope no one here misunderstands. I am not trying to start a flame war. This is something that I have had to fight about when I tried to convince the owner to switch away from using PLCs. He would say·"the customers expect PLCs and they will not buy our product if there are not any in there." I could definitely see how this chip could easily control the simpler machines that we build. It would require designing a PC board that would handle (8-10) 24 VDC inputs and (6-8) 24 VDC outputs. This is the part that may be hard to justify when you only make 40-50 machines a year and the part you are replacing only costs $130.
Thanks in advance for your time.
Bob
Comments
$130 which dollar US dollars ? Australian Dollars ?
We are looking at building a PCB with a Propeller on it (DIP 40) and keen to see what
market is out there for this unit.
Ronald Nollet Australia
http://web2.automationdirect.com/adc/Shopping/Catalog/PLC_Hardware/DirectLogic_05/PLC_Units/D0-05AR
It is $119.
The programming software is $395 (one time cost) and the programming cable is $30.
Now I think that the propeller is a better device as a controller but I do not think I would be able to get the overall price down to compete with this. Especially if·I was going to do a one-off.
That would be a counter for balls used for underarm deoderants ..!! .. Ping Pong may be an option though !!
Currently there are 8 of those machines - and I am looking at a further 16 for the sister plants. There is not a great deal with regards design over heads - due to the fact that the prop is so configurable - you decide what are inputs and outputs - the program is easy to modify - the spec. for those machines started as a counter requiring a large human readable screen. Since it has progressed to incorporate rework counter and update shop floor data collection system and now uses a higher resolution display (thanks to Chips tile driver sample). With futher enhancements due also. I simply can't recommend it highly enough. The simplicity of the hardware required has raised eyebrows and has led to orders for machines specifically requesting the 'same control' - to me that says it all..
Regards,
Quattro
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'Necessity is the mother of invention'
Very interesting. How did you handle the sensing? I·have used 120VAC and 24VDC diffuse reflective and through beam sensors (like Banner). Also, is your display a touch panel? That seems to be very big right now. Everyone in the Pack Expo features touch panels on many of their machines. Does the 3.3V Power Supply supply enough current to allow switches to be placed up to ten feet away from the controller using 18 Ga wire? How much time do you allow for switch debounce? Is it possible to use the EEPROM for recipe storage?
Lots of questions (hehe),
Bob
1) Sensing was with diffused retrofeflective sensors to optocouplers ..... 2) Display is not touch panel but would be a possibility ... not needed in this case... 3)I wouldn't be using the 3.3v in such a manner - I always use ind standard 24v DC for I/O and connected to Prop via opto couplers..4)You can use the boot eeprom to store data - in my case I used an second eeprom for this purpose..
Regards,
Quattro
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'Necessity is the mother of invention'
Post Edited (QuattroRS4) : 4/26/2007 2:21:22 PM GMT
if you want to use the EEPROM as data storage you should be use the 24LC512 version, because the Prop tool will always overwrite the first 32KB of EEPROM. So you could be store data in the second 32KB without losing it on a program update. You can find the Basic I2C Driver from Mike Green in the Object Exchange to read from and write to the EEPROM.
Graham
yes, of course it is possible. But it is not easy to calculate the correct address to update a variable in EEPROM if you have more than one object.
Bob
I have no experience with the Propeller (yet) but I often lurk in this forum collecting good ideas and preparing for the day when I will likely take the plunge and try to learn this device.
Your subject line caught my attention as I too am in the industrial automation line of work and have experienced similar lines of thinking. My employer has been using the Parallax line of SX chips in several projects. I think there are enough similarities that the rest of my post might be relevant to you.
"Why did you go with this particular device instead of using a PLC?"
In my case we chose the SX chips over a PLC because of the lower per unit cost (once developed) and the greater ability to allow for customization.
"I have worked in the packaging industry for 17 years and practically everyone uses PLCs..."
Yep, yep... I know it!
"How do you justify all the design time?"
For my company, we are hoping that the lower per unit cost and the design flexibility will offset the high cost of design over time. For example, one test fixture design called for two 24V inputs and six 12V outputs. This could easily have been handled by a PLC. Instead, I completely designed an opto-isolated 8-input/8-output selectable voltage circuit board with EEPROM and serial port capabilities. In essence, I over designed for that particular application but in ways that added general flexibility.
I expect that we took a loss on that initial contract. Later, the client ordered a few more units, some with two additional inputs. No problem! The circuit board was already designed for this. I just added the additional components and changed the software. Again, a PLC could have done the same job. However, we were now starting to recoup some of our investment as the components in our custom board cost less than a PLC.
Soon after that we won a contract to build some bar code reading machinea. They needed to be trainable to certain field changeable barcodes and handle some industrial I/O. I am not sure how well a PLC would have handled this application. I think most bids included an industrial PC. Our already designed circuit board could be programmed to handle this application also, which I think allowed us to place the low bid!
I mentioned customization as a key point and we are just now starting to realize that factor as well. Consider cases where our current circuit board which was as generically designed as possible is not able to meet the needs of a particular application. Even when this is the case much of the design work for a new device is already done and needs only to be copied over to a new design. Once things like opto-isolation for specific voltages, EEPROM and serial support, etc. are figured out you can reuse those design blocks much like you reuse software code. We expect this ability to allow us to place lower bids for custom designs.
"Also, how did you convince your customers to go along with accepting that this device was in their machine and that their techs would probably not be able to modify it?"
I understand the problem and in our case the simple answer is most times we do not convince large companies of this. We build with PLCs for those clients who expect and demand PLCs. Other clients "just want the machine to work" and do not really care how it works. Those clients do not care about modifying the source code in our custom PLC replacements. (We do not provide it.) However, they can adjust certain parameters as called out in the design.
I wish we could convince all of our clients to accept a custom PLC replacement when applicable but, as you have observed, this is a very hard idea to sell sometimes.
I hope this provides some insight into how someone in a similar field is trying to accomplish similar things.
- Sparks
Your make-or-buy question is one which has aroused developers and managers since the wheel was invented. To answer it requires a dispassionate analysis of the benefits and the costs of rolling your own versus something that you're already using or is readily available elsewhere. If it's something you're contemplating building yourself, you have to ask what extraordinary benefits will accrue from it. Is it something that nothing else can do for the amount of money you end up spending to develop it? As for the costs: remember that development and customer support costs have to be figured into the per-item price. With a contemplated net production of only 40-50 units, the benefits will have to be very special, indeed.
Another thing to consider is this: If you invent it, you own it. Translated another way: If it breaks, you're the one who has to fix it, because nobody else will know how. If somebody has a question about how it works, you're the one who will hear about it. Being indispensible may lead to job security, but it's a rotten existence. Your boss is right to be cautious. Automation Direct makes nice equipment for cheap, it's everywhere, and lots of people understand it and know how to program it.
In my own experience, I'm faced with upgrading a painting machine I built 17 years ago for a friend of mine who owns a fishing tackle company. It uses two brushed DC gear motors: one for advancing a "dip station" and one for dipping the lures into the paint. The motors are a constant headache because, as the brushes wear out, their characteristics change. The obvious solution is to switch to brushless DC motors. So initially I thought I'd replace the homebrew Z8/PIC control system I built with something that uses a Propeller, which could handily control the brushless motors. But here's the catch: my friend wants to send the machine to his contract plant China. That changes everything. If I invent, I own it; and I don't want to be the only person who knows how to fix a machine that's in China! So now I need to find the blandest whitebread, off-the-shelf parts that will do the job and run from both 110VAC/60Hz so I can test it here, and 230VAC/50Hz so it will run over there. And as much as I detest ladder logic, it's what the industrial world understands, so it's probably what I'll end up using.
Now, having said all that, there is a way that both you and your boss can get what they want. You do this by leveraging something you already have by adding something new to it, rather than replacing everything and starting over. For example, the Automation Direct PLCs have a communications port that allows you to plug stuff in and send data to the PLC or receive data from it while the PLC is in operation. The port also provides 5VDC with enough available current to power some pretty exotic stuff (e.g. a Propeller-based gizmo). What's more, this port uses a protocol which is freely published, so you don't have to reverse engineer anything or go digging for details.
The photo below shows one such example. It's a DL05 into which a Parallax MoBoStamp-pe is plugged via an RS232 daughtercard (still in prototype form). The other daughtercard is the retooled and soon-to-be released TAOS TCS230-DB color sensor module. Together, these items comprise a complete color-sensing and control system. It uses the DL05, because it's cheap and uses ladder logic, which plant engineers understand. And it incorporates a color-sensing subsystem that's programmable in PBASIC.
Eventually, the PropCAM will have a similar, Propeller-based board to plug into (the MoBoProp) and could thereby interface to Automation Direct PLCs in the same fashion. But the point is to leverage the known, ubiquitous, cheap stuff that's already out there, which people already understand, and which do their jobs superbly, with something new. That way you get the new capabilities you want, and your boss gets to keep his PLCs.
I guess I got a little long-winded there and threw in some shameless commercial plugs for my own stuff. But your situation so closely dovetailed the thought processes that led to that stuff, I couldn't resist the opportunity. Nonetheless, I hope these comments have been helpful.
-Phil
I work as currently as an Electrical Controls Engineer, on production machines. Motion controllers (Simotion D) and servos are obviously the best fit.
Where I would see the Propeller chip fitting in, is a really cost-effective way of doing a video display while doing simple digital control. It gets to be really expensive when having to add in an HMI Panel just to display some simple numbers and some indications from a PLC, basically doing like what QuattroRS4 did, on a big monitor screen. I have yet to find an HMI that wasn't dog slow in updating the screen, and where the editing software didn't cost a small fortune and be buggy and annoying to work with.
But even moreso, the propeller would be perfect in an application where you needed to generate interesting sounds (tones) or had the need for unconventional input on a simple machine with a mouse or keyboard, but without the desire to bring in a PC.
What would really be great is to allow updates over a telephone modem (like PLC's do), with the bonus of being able to change the way the display looks in the same download! Unfortunately with the way Chip designed the programming method, it would require software running in a cog to simulate a monitor program or somesuch, and the software would have to be very careful not to overwrite EEPROM unless it was sure the download was correct. But worst case you'd be flying out there anyways.
Just my opinion on the matter.
I'm a medical OEM... but many of the process and control issues are the same. I can't see how anyone could change from a known solution for 40-50 units a year, with a part cost of $130.
If you try to argue the issue on those grounds, you are going to lose the argument.
The rational has to be a tangible future value to your company. In terms of manageable, re-scalable and re-useable development, the Prop is the one. AND in terms of the vertical and horizontal integration potential, the Propeller is fabulous.
As part of a larger development effort in similar markets or in emerging markets that aren't settled yet, the Prop makes bottom line sense.
The Prop already has sex appeal...and as advanced applications start to role out that sex appeal is going to sky-rocket.
Finally, while the jury is still out on this issue, I personally think that the Prop is different enough from everything else, that there is almost always a reason for developing around it. I would expect companies to offer a broad range of component solutions to service Prop based applications, pushing in-house development costs way down. That is a potential market could easily interest your company.
Rich
One project we did was for a waste management plant, where a state-mandated procedure had to be followed in case of a spill in a parking lot. Actions depended on specific amounts of accumulated rainfall and a complicated schedule of passage of time during and after rainfall. The microcontroller (Our OWL2pe Stamp, but could be a Prop), fed the rainfall data with timing criteria as a few yes/no inputs to the PLC, to enter into its ladder logic, and also it could log and display ceratin activities of the PLC for a verification record.
Glue projects seem to turn up frequently. People who have these projects always seem to think that their's is the bees' knees and everyone will want one, but I am always skeptical. But the point is that there is no end to projects like that. There is probably somebody out there who needs to interface smoke signals to BACNET, no kidding.
My projects are more in environmental monitoring and instrumentation than in industrial automation. Most often a PLC is out of the question for these instruments due to their power requirements and due to their self contained nature. The propeller is highly exciting for these projects where the end result is largely a self contained box.
It is true what Phil says, we own it after we invent it, and support is especially difficult when the project is in a remote location or in a rural area in a developing country. But I would have far more confidence to send a compact project based on a BASIC Stamp or Propeller into that environment than I would to send anything based on a PC or PLC. There are many issues.
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Tracy Allen
www.emesystems.com
Post Edited (Tracy Allen) : 4/27/2007 3:47:53 PM GMT
The other way to break the equation, which depends upon the business philosophy of your company, is to make a small jump into related businesses, which might compete with your suppliers or better yet into an area of products or services to which your suppliers could subscribe... that is vertical integration. I know of some huge companies, which got that way by systematically avoiding vertical integration... so this kind of proposal very much depends upon the business philosophy of your company.
You might not know unless you ask.
Rich