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I am looking for a plc system for our brewery. I would like buy a second hand PLC with the necessary modules. I have seen the AB SLC500 1747-L542 cpu for a good price (120$) with a lot of modules, but I dont know, if it is new enough for a project. (Windows compatibilty, programming environment, etc)
Should I buy it, or it would be a bad decision? If it is not a good decision, what do you suggest for me? I have seen Siemens S7-200, Siemens ET 200 and others too.
Thank you.
If you want to go cheap, use something from automation direct or ez automation. You not only need a CPU, you need I/O cards, rack, power supply, software & HMI. That's going to be a ton of money up front. With the two vendors I mentioned, they bundle most of that for a much lower cost of entry.
Yes this is certainly new enough to use. However, you will need an entire rack. For instance, a ethernet, devicenet, or io cards to connect the processor to your components.
Also as Bill J mentioned, AB may be industry standard in America, but it is expensive. Depending on your brewery's income it my not be smart. Siemens is the same idea.
Quote from AB's website
Our Bulletin 1747 SLC™ 500 control platform is used for a wide variety of applications. Rockwell Automation has announced that some SLC 500 Bulletin numbers are discontinued and no longer available for sale. Customers are encouraged to migrate to our newer CompactLogix™ 5370 or 5380 control platforms.
link to website
So I would say, for a new project, no it's not worth bying in 2017.
Depending on how many points you need to use I would recommend going with the CompactLogix or MicroLogix from AB. The lowest CompactLogix is my favorit for all around tasks, I have standardized the whole plant to use it as the lowest level PLC for the simplest machines. Built in you get Ethernet capability, 16 inputs, and 16 outputs. You can expand the controller via different modules (up to 8 for the lowest PN), that can include additional discrete IO, analog modules etc.
Do not use a SLC as they are obsolete and even though you can get it to work without much trouble this is not a good choice for a new project.
It is hard to say what you need exactly without knowing the specifics of your project so I would recommend using the "integrated automation builder" (a free download from AB) to properly size a controller for your needs.
I am developing the firmware for a USB-based hardware device. The USB interface protocol requires that each device be assigned a vendor ID (VID) and product ID (PID).
How do I, as a device manufacturer/designer/developer, acquire a vendor ID? It is my understanding that the USB-IF assigns and policies these; is that correct? Do I need to buy a vendor ID from the USB-IF?
What happens if, instead, I just randomly pick a vendor ID to assign to my device, or just enter 0x0000, 0xFFFF?
Vendor IDs are a scarce resource, just like OUIs (top 3 octets of MAC address) and IPv4 addresses are. They have to be allocated so others don't use IDs/addresses that collide with yours. The cost just raises the barrier to allocation, so everybody doesn't land-grab willy-nilly.
It would be nice to have a "private" range, much like RFC1918 addresses (10/8, 172.16/12, and 192.168/16), that people who don't care about collisions can use.
The only meaning of getting a vid and a pid is to ensure that your sub device will not affect other with the same vid and pid.
You could set the vid or pid you like but you get the risk of a collision and your driver or the one of the other device could stop working, or both.
Ref: http://www.usb.org/developers/usbfaq#12
One other answer that people have missed: It takes a surprising amount of money and time to run a standards body.
There are costs to host the web site and official repository for the standard. You have to setup your own server, or rent space with a hosting company.
A new standard requires marketing. If people do not hear about your standard, how are they going to adopt it and use it?
Are you going to demo the new USB standard at CES, IDF, Embedded World, or some other trade show? It costs tens of thousands of dollars to rent a booth and pay for construction at one of the big shows. It costs thousands in air travel and hotels.
Are you handing out pamphlets at the show? How much does it cost to have them printed?
Are you going to advertise your standard in a magazine? Or banners on a web site? How do you expect to pay for this?
It costs money to coordinate meetings between the various members of your standards body. If you want a face-to-face meeting, you have to rent a conference room somewhere. Are you providing snacks and coffee? If you want to do a conference call, who is paying for the phone service?
You probably have an e-mail list or discussion forum. Who is maintaining that? How are you paying for the disk space to archive everything?
Does your standards body have a mailing address? Office? PO Box? Phone Number? Fax number? How do you expect to pay for that?
Any standards body with more than 1-2 members is going to have a board of directors, bylaws, officers, etc. Who is running all of that?
At some point, you will want to incorporate your standards body so it is a "perpetual" organization, not just tied to you personally. That means you need to file a tax return. Who is paying for the attorney's fees? Do you want liability insurance?
For a "physical" standard like USB, you probably need to spend money building prototype connectors and testing them. You probably need a test lab somewhere with oscilloscopes and other equipment, not to mention PCs, cables, and other equipment. Before you build the connectors, you probably want to simulate them, both mechanically and electrically. The costs for doing this can exceed $100,000.
Are you designing the logo for the standard yourself in MS Paint? Or do you want a graphic designer to do it for you. Who's paying for it?
Do you want to register your logo as a trademark? Who is going to take pay the fees for that?
Beyond money, it takes a lot of time to run a standards body. In the beginning, you might be able to handle it in your spare time, but for a high-visibility standard like USB, you may need someone dedicated to the standards body full time. They will need a salary.
The money to run a standards body has to come from somewhere.
You can charge membership dues, but this may not be enough. You will find that only a handful of people actually want to contribute to the standard. Everyone else will simply download the spec from your web site and benefit freely from your hard work.
You can charge for Access to the Specs, but this gets the "open standards" people up in arms. It also hampers the adoption of your spec. Not to mention people will probably just share the PDF illegally.
The simple truth is that a $4,000 annual membership fee is a pittance for a USB device manufacturer. You will spend far more than that designing your product and manufacturing it. The people who balk at that cost were probably not serious about building a USB device anyway, and would just "waste" the USB vendor ID (there is a finite number of possible IDs).
I've never found an official public listing of VIDs.
Seems to me that usb.org should provide one as a general service to the USB community, and if a vendor didn't want their VID public usb.org could just list it as "private" (it could well happen that a company wants a VID for internal use only)
The best list I've found for VIDs (and many associated PIDs) is here:
http://www.linux-usb.org/usb.ids
It's updated frequently, but I have found errors, so caveat emptor.
Does any other provider offer a cloud computing + storage layer like S3/EC2, with free data transfer between the two layers?
I have looked at:
Softlayer CloudLayer Storage -- no free transfer between the cloudlayer storage and cloudlayer computing instances.
Rackspace CloudFiles - Quite a bit of marketing mumbo-jumbo, and something about Cloud Connect, I gave up on the site once the Live Chat CSS Popup started following me around.
Does anyone know of any others?
I'm looking to store some large (non-random access) files for constant re-processing on a storage solution, and process it nearby, without paying transfer costs daily (looking to store in the 500-2000GB range, re-processing it all daily).
Re-processing requires a (Linux) server with a "decent" (weasel word alert) configuration.
Thanks!
'Cloud computing' is a bit of a myth.
They're all just, essentially, virtual private servers. 'Cloud' instances tend to have the flexibility to be billed by the hour, rather than monthy, but they're still just a VPS.
Persistent storage is a useful feature from a very limited number of VPS providers, but one that can easily be emulated by having two+ VPS' in the same data centre (Linode are an excellent VPS provider with free local data transfer, sadly they're rather limited by capacity). I don't know of any other VPS/Cloud providers who offer their own persistent storage solution.
It is something you can easily achieve yourself. VPS servers tend to be a little restrictive on hard drive capacity if you're looking for 500-2000GB, Perhaps you could consider a dedicated server and handle storage and processing on the same machine... you can't get data more local than the same machine!
First, the short version: stop looking for “free”.
Now, in more detail: you're looking to consume some somewhat-non-trivial computing, data storage and networking resources. Presumably you've got a good reason for doing this; if you truly have, you'll have the ability to also purchase the resources required for what you want to do. There are a few options on this front, none of which are free:
Buy and host your own hardware.
Buy the hardware and host it in a colocation facility.
Hire the hardware
Long term hire
Short term hire
All the Amazon are doing is short-term, easy set up hiring of resources. Their prices are quite keen (if some other option is cheaper, it's because it is missing something significant that Amazon do; maybe it's something you don't need but that's up to you to figure out). You can host the core of the Amazon API quite easily on whatever resources you've hired (see Eucalyptus) but be aware that going from having the software and the API to having everything work smoothly is a really big step; the more I work with Eucalyptus installations, the more impressed with Amazon I become. And that's despite being also pretty impressed with Eucalyptus itself.
But none of this is free. It takes real resources to provide – e.g., electricity to power the machines and keep them cool and a building to house them in – and ultimately, that's got to be paid for somewhere. To expect otherwise is to believe that others should have to pay for things for you; it's pretty rare that that happens, and the more you need to consume, the rarer it is (especially if the economy isn't doing too good). So stop thinking in terms of how you can get it for nothing (“freeload”) and instead take a good look at what it really costs to provide through various routes and seek to minimize your costs. If you can't afford even that, your #1 problem isn't hosting but funding; fix that first.
Rest assured you're not alone in this matter. This is what lots of other people worldwide have to do to make their projects into reality. Good luck!
GoGrid has an external storage with free transfer and access over typical protocols like SMB, NFS, rsync, FTP. The first two allows for mounting as normal drive.
Note also that many providers will allow you to create cloud servers with 2 TB instance storage. For sure not able to name all of them, but you can find some with cloudorado.com .
As described before, I work in IT consultancy and move through various customer environments. It is natural to encounter a variety of security policies, and in most environments we have had to go through a security checklist before authorizating our laptops - our mobile development workstations - for connection into their network (most of the time just development network).
There is this customer who does not allow external computers to connect to their network, so our laptops are.... expensive communication computers with mobile GSM modems. We are forced to use their desktop PCs for development, and those workstations are pretty old models with low RAM and single-core Pentium 4 CPUs and cranky disks. Needless to say, development work is sub-optimal, especially when working with Visual Studio solutions that can range 100 - 400 projects.
For small cases that can be isolated, we develop and test on our own laptops. But for the bigger cases, given that certain development servers like SeeBeyond and mainframe DB2 databases are only on the network, and the prospect of copying hundreds of projects to and fro machines is just ghastly, it does not seem like a technically sound idea.
I am not asking for tricks that violate the customer's policies (e.g. plug laptop in masquerading desktop MAC address). I just like to know what others have tried to retain some of their advantage and efficiency with their own hardware when working in such environments. Whenever I can I try to duplicate the environment with virtual servers on my own laptop, but it only goes so far with Microsoft-only server solutions. Virtualizing non-Microsoft server and software is a challenge.
That's tough. The root cause here is management that doesn't understand that there are real cost implications to their choice of environments.
Your problem is that while you may be billing by the hour, you probably aren't getting paid that way, so your customers' wasted time goes into the pockets of your boss and not to you. A lot of times, this presents a mild conflict of interest. Your company has about zero incentive to speed up your work, and your client doesn't want to make an infrastructure investment in what they see as a temporary engagement.
All I can say is that you have to run this up the flagpole with management. You have to show them that this is taking real time from the projects which could put your deliverable dates at risk, or worse, the reliability of these machines is such that it puts the delivery of the end product at risk as well. The onus is on you to make your management into a believer.
A gig of RAM at Crucial is thirty bucks. If nobody is willing to shell out 90 big ones for 3GB of RAM for your box, you have management that's actively working against you or does not respect you. If it comes to that, you've got bigger problems and need to look for your next employer.
One of the things that I did when I upgrade my current development environment was find links to productivity studies that showed how much productivity increased when the development environment was enhanced. In my particular case it was going from 2 to 3 monitors on my desktop. I was able to find 3-4 articles that described how much was gained by having the extra monitor. It seems self-evident to me that you'd want a newer, well-configured system for developers, especially since the cost of the hardware relative to the cost of the people is so small these days, but the bean counters often think differently. If you can go in armed with some industry studies that show productivity gains, I think it will be harder to dismiss your concerns as just complaints about the environment.
FWIW, I was disappointed to have to do the research for an upgrade that cost less than what the department would spend on paper in a month, but sometimes you have to do things that make no sense to you because it makes sense to someone else.
Write a decent proposal to your manager, that's about all you can do to rectify the solution. If he is unwilling or unable to fix the problem, or unwilling/unable to pass the proposal up to someone who can, then I'd say the current situation is what they've decided to use.
In that case, either live with it, or don't, ie. move on.
The proposal should contain:
A proposal for what you want done
Why it should be done
The consequences of doing it
And most importantly, the consequences of not doing it
List things like longer development time, or less testing, or less time to write quality code. Basically, a minor upgrade that doesn't cost much will improve the quality of the product tremendously.
I just went through this and found a pretty good solution : get a different job
Just synchronize incrementally. You're not typing that much code/second a gsm connection cannot keep up with it? Make sure your projects are setup to use mocks/stubs whereever possible.
Setting this up probably is beyond the capability of the systems administrators of your customer.
The dependency on the big databases should be reduced so you only need to run daily regression tests.
When selling a software package that requires hardware, typically dedicated hardware (could be a VM), the buyer typically has to buy the server it will run on. So the total cost of ownership (focusing on the capital expense) includes the hardware in addition to the software.
For example, a $3000 bug tracking package might need a $1500 server to run on, total cost is $4500. The hardware is 50% of the software cost, or 1/3 of the total cost.
Of course, with open source packages, the ratio is inverted.
So the question is: does it matter? At what point does hardware expense affect the sale of the software?
Why require hardware at all?
If hardware prices are a big breaking point in your sale, perhaps offer a hosted solution and factor the price into this service.
"Software As Service" might really help you makes some sales for customers with limited infrastructure.
The ratio depends on which part of the equation is the commodity part.
If you are selling a software targeting solving complex problems like air traffic control that can run on any servers, you might want to sell it packaged with the hardware for a bit more, but since the hardware is the commodity and can be obtained from other vendors, the price ratio will be heavily skewed towards the software.
If on the other hand you are OEM and your goal is to sell your hardware, you can use the software as the commodity to bring more value to your offering. For example, you can sell high-endserver machines and add a preconfigured LAMP stack to make your offering better. In this case, the price is heavily skewed towards the hardware.
"typically" - that's an assumption.
And the cost can be more than just hardware and software if there are service or renewal fees involved. This can be true of open source as well, because a lot of companies like to pay for indemnification and services.
If you buy hardware plus operating system, the decision to go with Windows or Linux comes into play.
I doubt very much that there's a meaningful, fixed ratio. It's an interesting question, though. You'd need a LOT of data, and I don't see that it's been gathered into one place.
I had another thought in a comment below that's worth surfacing. There's another consideration that's becoming more important all the time: power consumption. Some corporate data centers can't add a new server without retiring an old one or by reducing power consumption some other way. Being able to deploy a new software purchase on an existing server is big plus. If it can be virtualized, even better.
So it's not always hardware and software. Other economic considerations, like power cost, have to figure in.
I have found that hardware costs rarely affect the decision.
Small companies can get away with reusing servers.
Large companies already support clusters of servers, increasingly with VM capability so it's easy for them to deploy/redeploy software to as much hardware as necessary.