Labview client server communication

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Labview client server communication

With DDE, applications send messages to each other to exchange information. For example, one simple message is to send a command to another application.

OPC with LabVIEW Software Options

Other messages deal with transferring data and referencing the data by name. All applications communicating through DDE must be running, and all must send Windows their callback function address before DDE communication can begin. Windows calls the function when you send a DDE message to the application. After establishing a connection, the client can send commands to the server and change or request the value of data the server manages.

You must use a network dynamic data exchange NetDDE server to establish a conversation with an application across the network.

LabVIEW and Qt Client/Server Communication with TCP/IP

Figure 1. Requesting a List of Microsoft Excel Topics. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Monitoring State Item.

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Figure 7. You are here:. Development System. Building User Interfaces. Printing and Publishing Data. Distributing and Documenting VIs. Hardware Input and Output. Analyzing and Processing Signals. Programmatically Controlling VIs. Communicating with External Applications. Operating Systems.The client-server application framework provides an example of how to set up a script-driven application using these building blocks.

When you need to set up an application that must be highly configurable or where performance and stability is an overriding concern, this framework provides a good starting point. Use the VI Package Manager to install this package to your system. When asked to replace already existing files answer affirmatively. When setting up an application there are matters of architecture and policy that need to be arranged for. These include initialisation, configuration, access arbitration, security, as well as means of handling or logging errors and warnings.

Policy tends to be fluid. By setting policies through scripts they can be easily changed even after deploying the application as a built executable. Architecture is more static, but when a LabVIEW-based architecture needs changing it tends to be painful because LabVIEW is compiled, lacks adequate abstractions for high-level programming, and ties code up with wires. The framework has a script-based architecture that provides ample flexibility for projects with evolving requirements.

labview client server communication

The framework is split into two components. The server is fully coordinated through scripts, it does not have a user interface. The client provides a start menu for an extensible set of GUIs. To give both components a try, start both the server and the client.

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Password fields can be left empty because none are configured for the example server. To run the server on the Mac, some paths specified in scripts may need adjustment [ 1 ]. The server is set up in analogy with the boot procedure of an operating system.

It consists of a series of scripts that arrange for the global configuration, registration of functions, and the configuration and starting of system services. Though much simpler than a typical OS boot procedure, the purpose of these scripts is the same: to support a freely configurable and selectable set of services and tasks.

The server is very lean: in its bare form it consists of a relatively small number of VIs that have only a couple of dependencies on VI.

An Asynchronous Multi-client TCP Server in LabVIEW

Any further functionality is dynamically loaded and linked, and is therefore optional. The following sections will discuss the various stages of initialisation of the server. The bootstrap script registers a selection of Lua for LabVIEW functions for later scripts and configures global system settings. By placing all scripts and other resources that define the server inside a resources directory and accessing them via relative paths, moving the server resources around or choosing between independent server configurations becomes a simple matter of redefining this one absolute path.

Switching between wholly independent server configurations is prone to replication of functionality. It is therefore often preferable to instead perform conditional initialisation and configuration within the context of a single set of resource scripts. Its job is to configure remote access of the server by clients. Note though that it is possible to run both client and server inside the same runtime, which is convenient during development.

In addition to the standard VI-server configuration settings, you can configure passwords for the two access levels operator and observer as well as specify a timeout for the highest operator access level. Please refer to the comments inside the access script for details. As shown below, multiple clients can connect to a single server.In this article, we define LabVIEW remote monitoring as acquiring measurement data from a distant location e. Caution : there are lots of different options with varying degrees of completeness to use here.

Featherweight FTW was designed for communication across distributed applications and endpoints. It solves most of the usual problems that someone would have to figure out creating a communication architecture from scratch using lower level tools like TCP or Network Streams.

As a result, it can take less time to learn than to develop your own, despite the learning curve. Remotely monitor variables with the SystemLink UI. SystemLink is a piece of software developed by NI. SystemLink is used for monitoring embedded applications running on NI hardware that have been built specifically to publish data to SystemLink.

View Larger Image. So what might you want to remotely monitor? Featherweight What is it in a nutshell? What remote monitoring scenario is it best suited for?

What should you know about it? Viewpoint is both a user and a contributor to Featherweight, and we maintain our own repo. The cool part about Featherweight from a remote monitoring standpoint is that the infrastructure is in place for remote monitoring; you just need to provide an IP address. The inter-process and intra-process communication are handled exactly the same, so a Featherweight actor can communicate with a remote application just by knowing the address of the remote process it wants to communicate with.

The Featherweight framework handles the underlying TCP messages. NI InsightCM We like this method when the application revolves around monitoring of rotating machinery. What is it in a nutshell? InsightCM is condition monitoring software targeted for rotating machinery. Condition monitoring for rotating machinery.

Sophisticated application with built-in device fleet management, analysis, alarming, displays, and so on. Configured data acquisition devices connect to an on-premise or cloud-hosted server. It has a specific architecture that provides some basic out-of-the-box functionality. If you want to modify it, you should not be a novice. This is not generally going to be a recommended method. Documentation is limited. UI functions are limited.

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The downside to this method is that it can be slow because you are sharing the entire desktop instead of just the application data. This method also relies on having a full PC with the appropriate remote desktop application on it rather than a lightweight client, such as a web or mobile app. WebDAV — this is a file sharing method. You may need to contact your cellular provider to enable this device to connect to the cell network.

Share this resource: facebook twitter linkedin reddit. This website uses cookies and third party services. See our privacy policy for more info.TCP is a great way to pass data back and forth between two networked systems. Next, open TCP.

You can launch multiple clients and they will all connect simultaneously. If you stop a client, the associated handler will automatically stop. If you stop the server, all handlers will stop. The server simply listens for TCP connections in a loop, with a 1 second timeout. If it connects, it saves the connection in an array and asynchronously launches a TCP handler and passes the connection reference and remote port to the handler.

The TCP Handler code attempts to read a packet and, if it receives one, echos the received message back, along with the remote port number. The handler continues to run until it receives an error other than a timeout error code This ensures that the handler will close if the connection they are handling is closed externally such as when the TCP Server or Client is stopped. Some additional error handling will likely be needed for your specific application, but I wanted to keep this example simple for demonstration purposes.

labview client server communication

Notice that the TCP Client does not need to know which handler it is connected to, it just simply opens a connection to the IP Address and Port and it connects. As always, if you have any questions or suggestions please leave a comment below. Thanks for reading! Like Like. You are commenting using your WordPress. You are commenting using your Google account. You are commenting using your Twitter account.

You are commenting using your Facebook account. Notify me of new comments via email. Notify me of new posts via email. Lets take a look at the code, to see how this works. Share this: Twitter Facebook. Like this: Like Loading You make it very easy to understand. Great job. Leave a Reply Cancel reply Enter your comment hereI have 30 remote sensors over Wi-Fi to send data to a server with LabView.

This is fixed. The server have a router that communicates with the sensors and is connected to the PC by net cable. I want to find the most efficient way of communication from the point of view of resources and, most importantly, the response speed of the system, because I want to update the screen as quickly as possible, sending more data per second from sensors. I think I have only? Which method would you recommend? Thank you all in advance!

Go to Solution. I would use option three. I would have the server listen for new connections and whenever it receives a new connection it would dynamically call a VI which would then run as a task to service that one client. You could set a maximum number of clients the server would support if you wanted.

This method would be very flexible and expandable. BTW, your server would only need to listen to a single port. All of your clients would use that one single port to connect to the server.

Each client process could then post data to a queue that your UI is using to receive data updates. You could also use user events to pass the data to your UI. I generally prefer to use a cluster with a string and a variant to pass the data. The string is a message name and the data can be whatever is required for that particular message type. When you process the message it will know what type of data it should be for that message and can use the variant to data VI to access the data.

As for your 3 minute connect issue I suspect that your clients are trying to do some type of name lookup before connecting. Your solution is efficient, flexible and adaptable. But from the viewpoint of efficiency in terms of speed of response, to open a single port and decode the source of each message is better than Method 1?

I have used this method extensively and have not experienced any performance issues.

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The only different between N number of dedicated ports and a single server would be the time it takes to spawn the client processing task. Also, a single server would probably use less system resources since you only have one listening task.

Not to mention you don't have to coordinate your port number for each client. This code was developed several versions back. If I were to write it today I would use the "Start Asynchronous Call" method to spawn the client processing task. I assume you are referring to "Start Asynchronous Call". That was added in LV If you are using an older version the method I posted above works just fine.

I actually posted that library recently. You can find that code here.Moderator: jacobkornerup. Contact Login. This saves having to learn any Java to program a nice UI in a browser, plus you get all the advantages of having a completely stand-alone LabVIEW program.

Also, in my program, I just have a digital input rather than an analog temperature input, but again it works fine for the example. My deployed application looks like this: Deployed VI.

You do not have the required permissions to view the files attached to this post. Thanks for posting! I'm definitely going to recommend this pattern to people that don't want to take the HTML plunge. Javascript is on my "to-learn" list I'm comfortable enough with HTML so I'll definitely be returning to the browser method in the future, but the ability to code UIs in LV appeals to me more anyway.

Another thing I see is that you can still deploy the stand-alone client as a remote application as well. How did you deploy it so that you were able to access the remote panel? That is huge, because JS is also on my to-do list, at the moment I have no experience with it. Board index All times are UTC.

labview client server communication

Created by NI.Windows, Linux etc. Source Code — GitHub Repository. As of version 2. The library is a wrapper for the native functions and usage is similar. A simple example of how to use the library is shown below, along with a description of each VI. The library supports acting as a WebSockets Server. The library also supports acting as a WebSockets Client. Performs the appropriate handshake depending on whether the it is a server or client connection.

Note: A backwards compatibility layer is retained for legacy applications allowing upgrade with minimal application changes. It is strongly recommended to update applications to use the new library VIs. See the built-in help documentation for more information. This will increase compatibility with existing WebSocket servers.

labview client server communication

Please uninstall any previous versions of this package before upgrading. This WS client functionality has not been fully tested e.

Thanks Stuart V1. Thanks Martin V1.

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Your Name required. Your Email required. Your Message. Documentation As of version 2. This site uses cookies: Read our privacy policy. Okay, thanks.


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