I have a device that uses Modbus TCP. I want to read data from it and display it on a webpage (Without an in between server).
I have found a project that does almost this exact same thing as a Chrome extension:
https://github.com/Cloud-Automation/chrome-modbus
It uses this in the javascript code: chrome.sockets.tcp
I was hoping that I could do the same thing on my webpage using WebSockets.
It seems that websockets would work on my webpage (acting as the client), sending and receiving information from the device (acting as the server). It doesn't seem that websockets is affected by cors.
Does anybody have pointers on where I could start on this? (Or a javascript library would be great)
Is this possible?
Without an in between server will not be possible, unless your plc supports other protocol different than modbus (e.g. post/get).
If your plc is "completely closed" and you only have this port/protocol open, then you need an in between server that makes the conversion of modbus tcp to html. Using node-red as well as the dashboard and modbus flows, you can achieve it.
If you solved it other way, I would like to know how you did it.
I did get this solved without a server in between. I did it using Chrome Sockets link I also made it work using a cordova app for smart phones. Firefox has a sockets api as well, but did not attempt to figure it out for that browser.
I solve this using the PLC Connect in vb, i used vb to pass data in database and get the data through javascript.
Related
We have two applications, one called flexOS locally on "the server", and one called flexVisu remote on "the client". The first one is doing the job, collection data and such things.
Historically those two applications are able to communicate via TCP/IP sockets and a proprietary binary protocol.
Now we want to replace the client application flexVisu with a web page hosted on the IIS locally on the server. Every web browser on every device should be able to display these web page(s).
Firstly we experimented with an additional application (flexVisuWebServer) on the IIS side that basically hosted a web socket server and translated the json data from the client into binary data for the server and vice versa.
But this always requires a http connection and a wss connection to be open at the same time.
I don't know why, but I don't like the idea of using javascript on the client to handle all the data processing to display the server data.
I think that it would be much easier if I wrote an asp.Net c# application that handles the connection to "the server" via our proprietary TCP/IP protocol. That way no conversion of data between binary and json format must be done, and the web page itself can be also written in C#.
This approach much more resembles the current approach with flexVisu connecting directly to flexOS, the binary data is directly used to fill in Windows Forms controls.
What am I missing here?
Would the asp.Net application be able to connect to a tcp socket and use our own protocol?
[Edit: 2021-02-09 at 16:18 localtime]:
I managed to use our proprietary TCP/IP protocol to connect from the web server to the flexOS in the page_load of the asp.net web page.
So basically it should not be a problem to use the underlying library to read data directly from the flexOS.
OT: Should i post subsequent ASP.Net questions here too, or open some more questions?
We decided to follow this concept:
the webpage is using a websocket connection to our application flexVisuWebServer and this application uses our propietary TCP/IP protocoll to talk with flexOS.
I want to achieve following functionality and need the help for the same:
I have one server on which there is device connected that prints some bar codes based on pre-formatted command given to it.
Currently there is one desktop application which generates the command and does the job.
Now I want to do this via web, meaning there will be one webpage (say .aspx) and I want to achieve this by javascript.
I am able to generate the pre-formatted command required for printing but I don't know how to send the command to server, whether socket tcp ip or something else.
I have tried using node.js, socket.io, json-socket etc. but nothing is working,
If javascript is a fixed requirement, then no I don't think you'll find a direct solution. You will need to create an intermediary service that will translate websocket protocol to the tcp/ip protocol your software communicates on. I found a package called Websockify that has implementations of this kind of bridge in a few different languages.
Although if you are open to using Flash on the front end, and can meet the security requirements on your backend connection, then Flash socket API could work. I believe Java applets can also manage this.
I don't believe this is possible to do from inside a web browser. If it were it would be a huge security vulnerability (think about it, you visit an attackers page and all of a sudden your printer starts printing and every shared directory on your network fills to the brim with junk data).
You could run the command on the server (node/.net/anything else...) and have the web platform talk to the server to kick the process off. But that sounds kind of like what you already have set up...
Alternately, if you can change the software on the connected device you could try to give it an HTTP endpoint which responds to POSTs.
I have recently discovered HTML 5's support for the WebSocket protocol. I began idly experimenting with it and I decided to undertake a simple chat program project. For it, I'd like to be able write a WebSocket server and have it serve users inside of a blog post, using Google's Blogger website.
The server would be written in Javascript and would have all the code needed to send one person's "conversation line" to all other WebSocket connections connected to it. Later, I may implement "chatrooms" where each line is simply redirected to certain users.
My first question: would it be possible to create a Javascript-based WebSocket server? I've researched a bit, and it seems that all server implementations were in PHP or some server-side language similar to that. Would it be possible to write a WebSocket server with Javascript?
The server implementation would be inside of a webpage, so as long as the blog is up, the server would work as well. My blog can be found here. The client's code would be like this:
server = "http://imdmstromyf8imdcaptomysl.blogspot.com/post_that_handles_chat";
connection = new WebSocket (server);
The problem is, a WebSocket runs on its own protocol (ws:// or wss://), so changing "http://" to "wss://" would not work. Could I tunnel the WebSocket protocol through HTTP? If I did, I would probably have to use Ajax, but avoiding that is the reason I wanted a WebSocket chat program.
Blogger has a place where you can insert your own HTML; would it be possible to use PHP tags to delineate the code from HTML?
I would just like to know whether it's possible to do what I want, and if it is, some implementation tips or (even better) some example code to use.
"The server implementation would be inside of a webpage"
A server implementation is not in a web page. Not sure what you meant here. You may want to edit your question.
Node.js is library written in JavaScript for use on the server. Google this and you should find many ways of getting started on running a WebSockets. To connect to the client, you will be using JavaScript as well, which you should again select a library that supports web sockets.
Additionally, you will need to verify the client' Browser supports it.
You can look at browsers that support web sockets here
Here is a jQuery plugin for web sockets
I have been working on creating an application that sends a string from an android phone to a server and from there sending it to a Chrome extension. I am sitting with a few options to continue, I can convert everything to websockets, I can use normal sockets for android to computer and websockets for extension to server, or I can do some HTTPRequest stuff.
I am looking for suggestions on the best way to pull off this communication. I have a php server an android application and a chrome extension that need to be connected. If there is a way to connect the android application to the chrome extension without the server I would be happy to hear that too.
I need something secure and something that can be organized based on the correct person asking or sending information. So when someone sends a string from the android application the server stores it (probably using their gmail) and when the extension asks for it the server sends it along.
Also could the server just push the string to the extension without the extension calling it? This would occur after the initial websocket connection. I guess it would just store the IP address or something like that.
Any suggestions or comments would be appreciated I am just trying to make the most efficient and secure system I can come up with. I have done a significant amount of research about every aspect so I'm more suffering from information overload then anything.
Thanks in advance :]
Look into Windows Communication Foundation Services (WCF). That's what I have been using for my android applications working with a database - the .NET framework is great, and the services seem to be fairly dynamic.
http://msdn.microsoft.com/en-us/netframework/aa663324
I have created server daemon, that produces some data, like messages and so. But, what im interested in - client monitoring. For example i have web page, and i need to establish persistent Tcp connection to server and show all incoming data into textbox. I know it can be done with flash, but im searching for JS implementation.
Is it possible and what`s the best practices ?
What you're asking for is known as Comet. Plenty of server software and client libraries exist - see the linked Wikipedia page.
WebSockets is designed to solve this problem.