Connect to OPC DA server from LabVIEW - labview

I have to connect to OPC DA server from LabVIEW and read more than 400 tags synchronously/asynchronously. I know there is an option with NI DSC module to create LabVIEW OPC client.
The problem is I do not want to buy NI DSC license because it has overhead functionality and hence costs a lot.
I am curios if you had an experience to connect OPC DA server without NI DSC from LabVIEW.

In addition to Yair's answer I have found an very useful toolkit here for $295 that provides fast and simple mechanism to connect to OPC servers from LabVIEW. I have tested with trial mode and it seems my problems are solved with this.
http://opc-da.com/

The DataSocket Read primitive supports OPC, but my understanding was that it doesn't really work well with a large number of tags. My own experience with it was with a relatively low number of tags and years ago, so you will have to test for yourself, but it should be built into LV, so it satisfies the cost requirement. You could possibly also control the way you read the tags to work around any performance issues it might have.
Note that you will probably need to add DS support to any installer you build.

Related

Tapi working with Teams / other cisco systems

hi i'm currently looking at some new cisco phone systems and something on the wish list is a click to open account on our intranet.
I've been advised to look into tapi so I wondered if this worked with teams so I could create and test a solution.
i cant find any sample code younger than 4 years old so also wondered if this is fading out with the newer wave of unified comms
The current trend in the unified comms is moving to proprietary interfaces. TAPI does not really have decent facilities to deal with the addition of chat and video channels anyway. While some vendors seem to be willing to keep supporting it for some time, most seem to be designing new API's from the ground up (Teams Graph, Cisco WebEx, Alcatel Rainbow,...)
Specifically to your question: no, Teams does not support TAPI and there seems to be no intention to ever do so. None of Microsoft previous UC solutions (Skype for Business, Lync, Office Communication Server) did either.
If you don't want to develop/test straight onto your production Cisco, you may be able to get a VM version of the PBX with a trial/temporary license for software development purposes through a Cisco partner.

SQL installation on Amazon Web Services

Folks, I have question this morning that hopefully one of you techies can answer – during past few months, I have been heavily involved in preparing several SQL certifications study guides as it’s my desire to secure Microsoft Certified Solutions Associate (MCSA) or associate level. While I have previous experiences within this skill set and wanted to sharpen it by obtaining further experiences and hopefully securing this certification, it has been quite challenging setting up a home lab that allows me to create environment similar to what the big dogs use nowadays – windows server/several sql instances/virtualization and all that – due to lack of proper hardware or cost. In any case, my question today is to seek your advices and guidance on other possible options, particularly if this task can be accomplished using Amazons AWS – I understand they offer some level of space that can be used as playground or if one want to extend the capacity, subscription is an option. So, if I was to subscribe the paid version of it, is it possible to install all software needed to practice and experiment all needed technologies to complete and or master contents on the training kit. Again, I’m already using my small home network and have all proper software, but just feel that it’s not enough as some areas require higher computing power to properly test or rung specific areas..
Short: Yes
You can create a micro instance for free and install whatever you want on it. If your not familiar with using the CLI, it can be a bit daunting but there are plenty of guides online.
They also offer an RDS service where, they will allow you to set up a database instance and will maintain it for you but it's not free.
Edit
Link to there MS Server Page
http://aws.amazon.com/windows/
Azure is the windows cloud service, I think the comment was have you considered looking at azure instead of AWS

Setting up a web developer lab for learning purposes

I'm not a developer by profession. Therefore, I'm not exposed to real world technical problems that face professional developers. I read/heard about web farms, integration between different systems, load balancing ... etc.
Therefore, I was wondering if there are ways for the individual developer to create an environment that simulates real world situations with minimal number of machines like:
web farms & caching
simulating many users accessing your website (Pressure tests?)
Performance
load balancing
anything you think I should consider.
By the way, I have a server machine and 1 PC. and I don't mind investing in tools and software.
PS. I'm using Microsoft technologies for development but I hope this is not a limiting factor.
Thanks
Since I am new, SO will not let me post more than one link, so I compiled a list of links for you at a pastebin here.
alot of tools for this. i like
http://www.acme.com/software/http_load/
and http://curl-loader.sourceforge.net/
they both can simulaty much queries to your server. Run it from another machine.

Windows Mobile Development - Where to begin? [closed]

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Okay, I will shortly be starting down the path of windows mobile development. I know nothing about the subject really and I am looking for people with experience to let me know of any gottchas you may know of.
Right now I dont even have a breif of what is requied but the assumption is that the application will be very little more than a bunch of CRUD forms for updating data. The only other requirment knowladge I have is that the application will need to support offline storage when there is no signal avaliable. This in turn will obviously require some kind of syncronization when signal returns.
My initial thoughts are that the application will primarily be a front end to interact with a web service layer. Im assuming that WCF will be an appropriate technology for building these services? I also thought that SQL Server CE would be a good route to go down with regards to the offline storage issues.
Any knowlage that you feel is useful within this domain would be appreciated. Advice, links, books anything appreciated.
EDIT: It has been noted that there are two ways to go with off-line synchronization. To either use some form of message queuing or to use SQL synchronization tools. Could anyone offer a good comparison and introduction to these?
EDIT 2: After a little more digging I get the impression that there are basically 3 different approaches I can use here:
Emmbeded Database to query against then syncronization online, when able
MSMQ along with .NET remoting
WCF with ExchangeWebServiceMailTransport bindings using Exchange Server.
Now, there has been a nice few points raised on the first issue, and I think I understand at some level the issues I would face. But I'd like to get a little more information regarding MSMQ implementations and using WCFs new bindings.
Here a few words from my experience so far (about 9 months) of .net Windows Mobile development.
Well you are occasionally connected. (Or more likely occasionally disconnected). You have to choose whether you are going to use messaging with queues (i.e. WCF/SOAP/XML or something like it) or database synchronisation. I choose the SQL synchronisation route so I can't really comment on messaging. The SQL synchronisation route is not hassle free!
If you go down the sync route with SQL compact like me you basically have two choices. SQL Server merge replication or the newer ADO.NET Synchronisation services. If you choose the former you need to be really careful with your DB design to ensure it can be easily partitioned between mobile subscribers and the publisher. You really need to think about conflicts, and splitting tables that wouldn't normally be split in a normalised DB design is one way of doing that. You have to consider situations where a device goes offline for some time and the publisher DB (i.e. main DB) and/or a subscriber alters the same data. What happens when the device comes back online? It might mean resolving conflicts even if you have partitioned things well. This is where I got burnt. But SQL Merge Replication can work well and reduces the amount of code you have to write.
Roll your own DAL. Don't attempt to use datareaders etc. directly from UI code and don't use typed datasets either. There may be third party DALs that work with Windows Mobile (i.e. I know LLBLGEN does, might be worth a look) but Linq-to-SQL is not supported and anyway you need something lightweight. The chances are the DAL won't be too big so roll it yourself.
If you are using .net you'll probably end up wanting some unimplemented platform features. I recommend using this inexpensive framework to give you what your missing (especially as related to connectivity and power management) - http://www.opennetcf.com/Products/SmartDeviceFramework/tabid/65/Default.aspx
Windows Mobile devices partially switch off to save power when not in use. If you are doing a polling type design you'll need to wake them up every x mins. A normal .net timer class won't do this. You'll need to use a platform feature which can be used from OpenNetCF (above). The timer class is called LargeIntervalTimer and is in the OpenNetCF.WindowsCE assembly/namespace (I think).
Good Luck!
SqlCE is only one of the options available for local data storage on a Windows Mobile device, and although it's an excellent database it has limitations. For one thing, SqlCE will not work (period) under encryption (in other words, if your user encrypts the location where your SDF file is, you will no longer be able to access the data).
The second (and most critical) weakness of SqlCE lies in the RDA/Merge Replication tools. SqlCE Merge Replication is not 100% reliable in situations where the network connection can drop during replication (obviously very common in Windows Mobile devices). If you enjoy trying to explain missing or corrupted data to your clients, go ahead and use SqlCE and merge replication.
Oracle Lite is a good alternative to SqlCE, although it too doesn't work properly under encryption. If encryption is a potential problem, you need to find a database engine that works under encryption (I don't know of one) or else write your own persistence component using XML or something.
Writing a WM application as a front end that primarily interacts with a web service in real time will only work in an always-connected environment. A better approach is to write your application as a front end that primarily interacts with local data (SqlCE, Oracle Lite, XML or whatever), and then create a separate Synchronization component that handles pushing and pulling data.
Again, SqlCE merge replication does this pushing and pulling beautifully and elegantly - it just doesn't work all the time. If you want a replication mechanism that works reliably, you'll have to write your own. Oracle Lite has something called a snapshot table that works very well for this purpose. A snapshot table in Olite tracks changes (like adds, updates and deletes) and allows you to query the changes separately and update the central database (through a web service) to match.
This thread I just posted on SO a few days ago has proven to be a great resource for me thus far.
Also the Windows Mobile MSDN WebCasts are a wealth of information on everything from just getting started up to advanced development.
I would suggest Sqlite for local storage. From the last benchmark I ran it was much better than SqlCe and you don't have to do stupid things like retain an open connection for performance improvements.
Trade-offs being that the toolset is less rich and the integration with other MSSql products is nil. :(
you might want to refer to this:
getting-started-with-windows-mobile-development
You shouldn't be intimidated for windows mobile development. It isn't much different from desktop development. I strongly recommend that you use .NET Compact Framework for development and not C++/MFC.
Some useful links:
Mobile section at the Code
Project. You would find a lot of
articles, a little digging is needed
to find the appropriate one.
Smart
Device Framework from OpenNetCF
offer valuable extensions to the
compact framework.
When you install
the Mobile SDK, you will find under the
Community folder links for the
Windows Mobile and CF framework
blogs. These are also valuable
resources.
Regarding your application, you are right about the WCF and the SQL Server CE. These are the proper ways for handling communication and storage.
Some hints for people coming from a desktop world:
You need to have some sort of power management. The device may automatically go to suspend state. Also, you shouldn't consume power when you don't have to.
Network connectivity is a difficult issue. You can register notifications for when a specific network (Wi-Fi, GPRS) becomes available or unavailable. You can also set the preferred means of communication.
Make the UI as simple as possible. The user uses his thumb and/or a pen and he is probably on the move.
Test in a real device as early as possible.
"24 Hours of Windows Mobile Application Development" from the Windows Mobile Team Blog has some good resources
If you can, try to start from the user use cases and work back to the code, rather than vice versa. It's really easy to spend a lot more time working on the tools than working on the business problem. And thinking through user requirements will help you consider alternate strategies, because a lot of the patterns you know from normal .NET don't apply.
I've done lots of intermittent application development of exactly the type you are describing, and an on-board database works just fine. The MSMQ/WCF stuff just adds conceptual overhead without adding much value. You need a logical datastore locally anyway, and replication at this level is a simple concept that you want to keep simple, so the audit trail is easily monitored and debugged. MSMQ and WCF tend to hide things in unfamiliar places.
I upvoted the SqlLite suggestion BTW. MS doesn't have their persistence story stabilized yet for CE.
For the database replication bit I highly recommend Sybase Ultralite. In terms of flexibility and performance it knocks the socks off SQL CE
I had to do this once. Weird setup with Macs for development, and we were all Java programmers. And a short deadline. PowerPC macs too, so no chance to install Windows for Visual Studio development, never mind that the money for this would never have appeared.
We ended up writing applications using Java, running on the IBM J9 virtual machine, with SWT for a user interface. Entirely free development stack. Easy to deploy. Code ran on any platform we desired, not just PocketPC/WinMob.
Most of the work was on the server side anyway - the database, the web service server. The logic. The reporting engine. The client side wasn't totally simple however - would get the form templates from the server (because they changed frequently), the site details (multi-site deployment), generate a UI from the form template (using some SWT GUI components that are wonderful for PocketPC development, like the ExpandBar), gather data with a point and click interface (minimising keyboard entry where possible), and then submit it back to the server.
For offline storage we used XML files on the device itself. More than enough for our needs, but yours may differ. Maybe consider SQLite?
There are a couple links you can check out to start with:
http://developer.windowsmobile.com
http://msdn.microsoft.com/en-us/windowsmobile/default.aspx
If you have a sticking point while developing, there are also Windows Mobile dedicated chats on MSDN that you can attend and ask your questions. The calendar hasn't been updated yet, but the next ones should be in January. You can find the schedule here: http://msdn.microsoft.com/en-us/chats/default.aspx
I am going to add an additional question to this post, as its been active enough and hopefully will be helpful to others as well as me. Ok, so after playing around I now realize that standard class libraries cannot be included in windows mobile applications.
Now the overwhelming advice here seems to be use an embedded database, though I now do have use cases and it appears that I will need to have document synchronization as well as relational data. With this in mind service layer interaction seems inevitable. So my question is how would I share common domain objects and interfaces between the layers?
"Document synchronization" - does that mean bidirectional? Or cumulative write-only? I can think of mobile architectures that would mainly collect and submit transactions for a shared document - if that's your requirement, then we should discuss offline - it's a long (and interesting) conversation.
Owen you can share code from Compact Framework -> Desktop, it's only Desktop -> Compact Framework that has compatability issues if you use certain objects that are not supported by the CF.
While a desktop lib doesn't work on CF a CF lib WILL work on the desktop, you can also run CF.exes on the desktop!
Just create a CF library as the project that defines your base objects / interfaces etc.
This book sshould e essential reading for all Windows Mobile developers: http://www.microsoft.com/learning/en/us/books/10294.aspx
For developing windows mobile applications you must have the basic tools like silverlight, visual studio, windows phone emulator and sqlite as your database storage.

Developing via Remote Desktop [closed]

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Has anybody any successful remarks about having a team working via Remote Desktop?
In many workplaces, we put end users via Citrix and the applications on a central, powerful server. Sometimes the clients are in the same building as the server, but often, they are remote.
There could be some huge benefits for me to put my developers on Windows XP or Vista instances running on a couple servers with Hyper-V.
I'm worried that RDP/RDC via the internet would be too slow for somebody to be able to develop efficiently.
I'm sure I can hear plenty of bad things about it... are there any people out there that have had success?
I have seen a situation where the attempt was made to do this with a sattelite office. It was done for a java development team using various java IDE tools. The result wasn't regarded as a success, and the company brought the team back into a central London office at considerable expense.
For someone doing this on a day-in day-out basis on interactive software, the result isn't really very pleasant. For something that mainly uses text-based tools such as vim and unix command line tools, it works somewhat better. At one point I had XVNC going over a 128 Kbit DSL link (of a type that was prevalent in New Zealand at the time) and could do work on an Oracle-based data warehouse at a remote location quite readily. The level of interactivity required by the tooling made them much less sensitive to the slow link than a Windows-based IDE.
So, I'll invoke the 'it depends' argument with some qualifications:
I would not recommend it for a modern IDE, and certainly not for something heavily graphical like Dreamweaver, BI Development Studio or Informatica.
For a textual environment like traditional unix development tools it could probably be made to work quite well. These user interfaces are much less sensitive to latency than a direct-manipulation user interface.
I'm something of a believer in the 'best tools' principle. Going out of your way to give a second-rate user interface to a development team will give off negative signals. The cost saving from doing this is likely to be minimal and it will annoy some of your team members. Even if it can be made to work reasonably well you are still making a value statement by doing this. Weigh the cost saving against the cost of replacing one or more of your key development staff.
We connect to our development environments using RDP and locally the performance is great. It slows a bit over VPN, but is still acceptably responsive.
Turn off all the windows animation functionality, desktop background, etc. and that will help considerably.
If you're not worried about the latency on audio and fast-moving imagery and you're not developing anything dependent on 3D hardware, you'll likely be fine.
I've never used it in a team environment, but I use my laptop RDP'd into my workstation all day and love it.
I've worked in an environment where we would occasionally edit some existing code via remote desktop. There were no significant challenges to this. As a developer I positively hated doing that work. Everything felt slow and unresponsive. However, we got the work done.
Thankfully these were often short 3-4 hours jobs... mostly fixes to existing systems on remote customer sites. I don't think I could recommend it as a normal way of doing work, but its certainly possible.
I've used both VNC and RDP over a DSL connection, running through an SSH tunnel, and have had no real issues.
There are definitely some lags, particularly if you're redrawing large parts of a screen. But most development involves small edits, and both of these protocols handle that very well.
I use Remote Desktop to control my Windows machine at work. I use a Parallels VM on a Mac and my connection is 2.5M down, 256k up.
This works really really well. I've been doing this for 2 years for 1-3 days a week. The slow upspeed isn't an issue - I can't type that fast.
I have 3 screens at work but still find a 20" Mac screen to be superior. The colours are much cleaner and I can work longer at the Mac than my work screens!
The thing that is a killer is Flash on a browser. If I accidentally open a browser on my remote machine with Flash it kills the connection. The solution is to use FlashBlock (a firefox addin).
I use Eclipse and Visual Studio with no issues whatsoever.
I've used it to work from home (remote login to my in-office PC via VPN).
The performance depends on your ISPs, of course.
It's slightly less reliable (because as well as your having downtime when/if ever the office LAN is down, there's now additional risk of downtime while either of the internet connections is down).
I have a remote server on a 1Mbps upstream pipe which I RDP to (over a VPN) and it works just fine. I even use large screen resolutions (1600x1200) with no performance problems. Of course, I'm not sure how such a setup would fare for multiple concurrent users, however.
A benefit of developing over RDP that I hadn't anticipated is that you can save your sessions--so after you get done developing for the day, you quit your RDP client and power down your computer, and when you log back in the following day your session is right where you left it.
As an added bonus, RDP clients are available for linux, and OS X.
I use RDP daily for development, I leave my laptop on at home with my work environment open and ready to go. When I get to work and everybody is loading up their projects and opening their programs I just RDP in and I'm ready to go. You have to keep in mind certain keyboard shortcuts that change though (CTRL+ALT+DEL for example), it is annoying at first but you get used to it.
To keep the latency to a minimum, I recommend...
turning the colors down to 256 (after all, you only need to see text)
Leave the wallpaper at the other computer
Leave sounds at the other computer
Leave any themes on the other computer
Choose a lower connection speed, even if yours is higher. Windows will minimize the data sent.
One of the advantages you might also consider is processing power. If your machine at home has far better specifications than your workstation on the job, compilation time is improved a fair bit. Since your local machine only needs to update the image from the remote machine, your local computer is not under load.
Using this option also allows me to keep on track. While others log in and browse the internet and waste time, I'm set up and ready to go. Being more productive helps you get paid the big bucks (if your employer notices), while others are still stuck in their junior programming roles.
Pre-2000 I did it for 3 years every day several hours a day. This was when bandwidth sucked too.
Nowadays it's much much better.
And if you use NxMachine life gets even better :)
I did not, however, use the machine with multiple users. My concern with that would be that developers are a finicky bunch (myself included) and we tend to push machines really hard as it is.
Can't imagine several folks on one box all deciding to compile :)
G-Man
We do it with citrix and is very fast.
I wonder what the reason for this would be. Does the central server(s) have access to some resources that the individual developer machines could not access?
I'm using RDP to connect from my home computer to my work computer from time to time. I have to say - it's possible to code, but it's way more comfortable to do it when the IDE is on your own machine. Even when on a 100MBit LAN there is some noticeable lag. Not enough to bother work, but annoying nevertheless.
If the people have to work from remote places on a regular basis, I'd rather prefer a setup where the central source control is available through some secure protocol (HTTPS, VPN, etc.), but the development can happen locally on the developer's machines. If using something like SVN, which works well even with offline development, then it should be way more comfortable for the programmers themselves.
What is important for a development workstation is sheer processing power. At our place the developers have the most high-end workstations in terms of cpu, memory, disk, etc and not in terms of audio and graphics. It's the latter that are most affected by RDP.
As long as the server that your developers are RDP-ing to is fast enough to handle multiple compiles, builds at the same time you should be fine.
As with all things, the answer to your question is "Your Milage May Vary" or YMMV. It depends on what the developers are doing. Do they spend most of their time writing code, or do they do a lot of large compiles? Do they need direct hardware access?
Do they need debugging rights? Once you grant them debugging rights, they basically own the machine and can interfere with other users.
It's typically much better to allow the users to develop on their own computers, and use a VPN to allow them to acces the version control system. Then they can checkout the files to their local computers and do whatever they want, then checkin the changes.
But, RDP has it's advantages too. You really need to weigh the pro's and cons and decide which list is longer or more "weighty".
I use NoMachine NX Client to remote desktop onto a headless server that runs FreeNX. It is great because I can login to my session from anywhere and my last session is still there for me. Speed has never been a problem, except when the DSL line is down.
Anyway, my point is that if you are running a Linux server and use 'vi' then there is a nicer alternative than 'screen'.