Hi,

I am using S7-1518-4PN/DP PLC, I want to communicate with desktop application/equipment over TCP socket/open TCP communication. As the desktop/equipment does not support any other way of communication. The equipment sending & receiving the data in JSON string format.

So I need the help how to do this/any application example?

even if is it possible or not?

Thanks

[Link: Library for Data Streams (LStream)]

Study of the documentation provided with the public library may be helpful.

Hello Ashok,

I totally agree with qwazee. The LStream library is able to decode a JSON string and provides you with all the key-value-pairs (kvp) in the JSON. As it is designed to handle things generic (for almost any JSON), it might be a little bit to powerful for your needs.

JSON itself is pretty simple to decode though. If you want to take on the challange to decode the JSON in question yourself, then I suggest to read the RFC 8259 (request for comments), which can be found at: RFC 8259: The JavaScript Object Notation (JSON) Data Interchange Format
You should also be familiar with parsing strings, before you start.
I personally find it satisfying, when I can try something and learn something new. However time constraints do not always allow for such things. In such crunch time situations LStream is the better call.

qwazee

[Link: Library for Data Streams (LStream)]

Study of the documentation provided with the public library may be helpful.

Massive warning using this library. The Deserialize function is full of basic programming beginners bugs, like wrong array offsets. Then overwriting the last element in the tree, not using the context of one element when searching for a value, and so on and so on. I wasted several hours fixing the errors, then I gave up and written my own parser, which also took magnitudes less memory if you have to parse a big json file but only need some specific values.

The http library has bugs as well, seems Siemens cannot read the RFCs. Seems all these libraries are written by students.