Nathan

MrPLC Member
 View profile  See their activity

  • Content count

    501

  • Joined

  • Last visited

Posts posted by Nathan

  1. Posted

    The dork in me is coming out - take a look at this! Sun's on to something building a data center in a standard shipping container. Amazingly innovative ideas in terms of convenience factors, power distribution, cooling, etc. http://www.sun.com/emrkt/blackbox/ Watch the flash demo. You'll be impressed.

  2. Posted · Edited by Nathan

    Crossbow's basic explanation of routing is good. Check out subnet masks to determine which computers are on the same network. The subnet mask is a way to define which nodes are on the same "subnet" (network segment). The entire address is 32 bits long and the mask tells how many bits identify the network versus how many bits identify the node on the network. The Class C (255.255.255.0) subnet that Crossbow mentioned has only 2^8 (255) addresses, but has 2^24 different networks. So, 192.168.0.x is on a different subnet than 192.168.1.x. This is where the default gateway comes in. I've posted similar content here (it also describes non-routable addresses): I'd recommend that you first learn how subnet masks work, then basic routing. After that check out the basics of DNS and ports. You'll be able to troubleshoot a TCP/IP network after that. It it will then be easy to get into fancy subnet schemes, bridges versus routers, NAT, VPNs, etc. I've been meaning to write a "TCP/IP networking for Integrators" guide that's simple and covers these types of questions. I'd be happy to answer more specific questions.

  4. Posted

    Paul, I believe FactorySQL restricts your performance times on the OPC end to about 50ms. The best way to test the database is to download a free copy of MySQL (or whatever database you want) and run it. Using a moderate amount of tags will run easily at that rate (<1000). Your system performance with respect to the database is based on tag count and update rate, and depends greatly on the system. That said, most integrators/end users that I've spoken with have been impressed by the response time. The big players "point database", "tag database", or "database dictionary" might be more of a relic from their own implementations before they started going with SQL databases. They implemented these in the first place because PLCs don't do well with many concurrent connections; the "point database" is a mapping to distribute that communication. I would argue that these vendors could implement their own proprietary "point databases" on an SQL database and get better performance (although they might need to keep tables memory resident and control their access to disk). This is not far from what Wonderware has done with InSQL. Much of the question has to do with licensing and supporting their existing customer base, not whether an SQL database can handle it. The question about Inductive Automation should address performance given that we've chosen an open model without a lot of proprietary optimization - in other words we could do a lot better if we forced you to use some particular database. For example, we'd use a trigger based notification instead of polling. We instead focused on supporting pretty much any SQL database type (MS SQL Server, MySQL, Oracle, PostgreSQL, etc). We haven't produced formal benchmarks since there are so many variables. I'd be happy to help you set up an evaluation to see how it runs for your process.

  5. Posted · Edited by Nathan

    I think the church does have the same opportunity to pay for the game if they want to. I can also see why the NFL would take action when it's policies about copyrighted materials are violated, particularly if the church is charging admission (why not separately ask for donations). I can also see why the NFL would allow organizations to show their content in public on smaller TVs free of charge. Showing the Superbowl on big screens brings in business to the organization, and is thus worth something to them. Why not charge for something THAT DOES COST THE NFL MONEY TO PRODUCE? The idea of more people breaking the law to make it acceptable is ridiculous! Should we all be allowed to steal pay per view movies because they're sent over the cable lines where we subscribe for basic service? The defense that the NFL would get a "black eye" in terms of publicity if it tried to enforce its legal right is even worse. Lobby for it! Contact the NFL or your local congressman (if you happen to disagree with copyrights). We have a legal process where you can make a difference. That said, I think the NFL's policy is ridiculous. They've chosen to support those who pay them for viewing rights at the expense of non-profits, who most (myself included) agree should be allowed. At this point they could make a very positive PR move to allow churches and other non-profits to view their broadcasts without charging. As an aside, I heard on the radio that the policy is that organizations that "An exception is made for sports bars and other businesses that show televised sports as a part of their everyday operations."I'm not sure how this applies to Church youth groups that may have been playing football games regularly.

  6. Posted · Edited by Nathan

    The OPC foundation offers sample OPC client source code to members written mostly in VB.NET. Writing your SCADA package as a generic OPC client is a good idea because it will allow the OPC server to manage much of the communication layer. More importantly, it will allow your project to be compatible with pretty much any OPC server.

  9. Posted · Edited by Nathan

    Tim, Thanks for the move. Does Vista allow you to override the driver thing? They were trying to do that with XP too, but (obviously) it didn't happen. The core (kernel) has been pretty solid in MS operating systems ever since at least NT 4. Drivers are really the things that have the permission and run level to mess with ("lock up") the user interface. Makes sense for them to do this move if they can pull it off. Unfortunately, it's worthless without a very high level of support and QC. I've used signed drivers that aren't stable. How MS can get all vendors to supply high quality/well tested drivers for most to all of their hardware is beyond me. In case you've never heard of this, signing refers to a cryptographic process that verifies the authenticity of the driver. This verifies that you're using a driver that: 1. Came from your manufacture 2. Was tested and approved by MS 3. Wasn't tampered with Disadvantages are that it cost money and resources to do this process and that it could slow down updates.

  11. Posted · Edited by Nathan

    Problems with networks tend to have to do with latency or quality issues, not bandwidth (which is what tends to increase as you add devices). Remember that the proprietary standards of not many years ago used to be on the order of 10kb/s, or less. "Slow" Ethernet now days does 1000-10,000x that bandwidth before even taking into account that old models often used a ring (one path), versus start topology. Bottom line - adding a few devices shouldn't be a problem.

  12. Posted

    Definably agree with Bob here. You can use panel mount PCs (NEMA 4X, if necessary) anywhere where you would have used a specialized panelview type device. Make sure to get the data in an SQL database so that you can easily access and maintain it.

  14. Posted · Edited by Nathan

    Now that Windows Vista has officially been launched - who's gone out and picked up a copy to run their local factory (some degree of sarcasm)? More importantly, has anyone started testing a controls project on Vista? Right now, I wouldn't touch it with a 10 foot pole for a real application, but you never know what customers specify. This would be a good place to put links for software company warnings and patches for Microsoft's latest and greatest.

  15. Posted

    I'm trying to put one together, but it's really hard to compare between different vendors features once you go beyond the basics. They vary in capabilities and implementation.

  17. Posted

    I wanted to throw a kudos to Rockwell support (and Ken in particular). I've spoken with several integrators, one who recently mentioned that it was easy to get through to a (helpful) real person and that the support went smoothly. I've knocked Rockwell tech support here based on experiences that I had four years ago as an employee of a Rockwell Certified Solution Provider. It sounds like this is no longer the case and the end user is benefiting from it! Nice job, Rockwell.

  18. Posted · Edited by Nathan

    I don't know of any good totally free OPC servers for AB PLCs, but if you need that functionality (not included in RSLinx Lite), you can give Kepware a shot. Their trial OPC server, KepServer EX is fully functional, but limited to 2 hour runtimes at a time. I think the only "free" communication drivers that you'll get are open source projects of questionable stability/maturity. What is your application?

  20. Posted

    Wandering - Lots of good advice here, did you get your question resolved? You don't need to worry about "fibre incompatibility" with industrial (ethernet) based devices. Basically you can treat on the PLC end like you're working over ethernet with the Fibre seamlessly connecting the distant ends. There are, of course, many different configuration/implementation options.

  21. Posted · Edited by Nathan

    Why not start with the vendor that makes your PLC? If it doesn't satisfy your needs look around for others. I've yet to find a good unbiased product comparison. (Please post a sites that may have these if they exist...)

  23. Posted

    Use Access, or better yet, a real SQL database. Since you're into VBA programming, you can actually write very cool/powerful GUI frontends in MSAccess that connect via ODBC. The weaker part of access is the underlying database engine (still better than .dbf approach). If you're going to invest the time to custom program this, I'd recommend using MS SQL Server as the backend. It will scale better, particularly for: backups, maintenance, and as users/data grows. You can accomplish similar programming within MS Excel. The SQL approach gives the additional option of Reporting packages from MS or others like Crystal Reports. Another nice feature of using a powerful database is that you don't need to generate an "hourly" report per say. You can create a window where the end user decides on the report type, duration, etc, and the "view" is dynamically generated at the users request. I don't know if a .dbf database satisfies this requirement or not. A properly indexed SQL database can quickly deliver LOTS of sorted data. Even Access will do well here. AB should have plenty of ways of getting data to an SQL/Access database. Hopefully it's builtin or a simple plugin. Depending on what you're doing, you might need Historian, Plantmetrics, or RSSQL. You could also use a 3rd party program to get data into the database like FactorySQL.

  24. Posted

    Check out FactorySQL and FactoryPMI from Inductive Automation. We always provide free tech support. If you're an integrator we provide free training at this point. The product evaluation is such that you can fully implement a system and run it (2 hours at a time, resettable), before paying anything. We're a relatively new company that is growing rapidly. I'll let you form your own ideas about us disappearing overnight. The best thing would be to sign up for a 1 hour web demo. We'll show you what we're all about and and answer any questions.

  25. Posted · Edited by Nathan

    Searching under McAfee in the Rockwell Knowledge base showed a lot of workarounds, exposing the activation/registration files that Rockwell works so hard to hide. I did find a workaround to using Launcher.exe. According to #24985, launcher does nothing more than display a splash screen and open vstudio.exe. Point your shortcut directly to vstudio and you should be fine. Ironic that the fix is a cheesy hack for the question posted in the knowlegebase (launcher.exe causes a fault in Windows), but actually very applicable to your problem (if it works).