TIA V13

The purpose being to exchange a number of information via sockets in TCP between the PLC and the pc with questions / answers
only in ASCII character, the data integer or boolean, I shall transform them into ASCII understandable for the PC.

For example:
PLC > computer contrives ascii " N of the barrecode ; weight of the parcel "
computer > PLC contrives ascii " N of the barrecode ; destination "

I can use the block TSEND_C then after TRCV_C
The pointer DATA aiming at a variable string in a DataBase tested on a hyperterminal with S7 1200, it works

But I am limited to the size of this variable by 256 characters.
May I point the sending zone and the reception area on " array of char"?
In every case I am limited by a number of character sends it as to reception?
( I did not find precision in the help on the block, and on the ethernet card)
I never know in advance the length of the sent and received(successful) data; thus to send it is not annoying,
I fill the rest of the array of char by spaces.
For the reception how does it take place? I suspect that the variable of reception has to be bigger than what we send me;
so aske me the question on the maximum?

<<May I point the sending zone and the reception area on " array of char"?>>
Yes.


<<In every case I am limited by a number of character sends it as to reception?>>
question is not clear for me.

<<For the reception how does it take place?>>
bigger or at least as big as the data coming in.

<<so aske me the question on the maximum?>>

Thanks a lot with this response.

I'm sorry for my english, I don't practise it often.

I think you answer this later with :

Fafner

<<so aske me the question on the maximum?>>

in one telegramm? i think if you are pointing on a very big area the function block divides the data and send more telegram.

<<Another way is to use more than one variable string ? and Send them in a short time ? The PC will understand like a one big variable string ?>>
that is depending on the application you are using on the PC.
the PC will get two telegrams and what he does with this depends on your application.

I undestand now what is a telegram. (never use this before)

So if my data is big (don't know yet how many bytes i have to consider) it is better to send more than one telegram.

On the PC, I can for example send one telegram with the information of how many telegram will be sent, and after send the data with 1 to x telegrams.

And the same when I receive ?

OR

The block functions make it itself ?

Anyone know this information ?

Anyone have an idea of how many bytes is the maximum in one telegram ?

Thanks

http://en.wikipedia.org/wiki/Maximum_transmission_unit#cite_note-4

I use the line ethernet V2 1500 bytes including the header

I can easily use an array of char [1..700] that is corresponding to 1400 bytes of data

It is not enough for me, because I have to send a big datamatrix code, so I have to split it in differents array of char. So I have to use more than one telegram...

Now it's time to find a solution with the application used on the PC.

- use a "flag" that says it is the end of all telegrams

- use a header in the first telegram that says how many telegrams will come

Right ?

But if the block function TSEND_C divides the data and send more than one telegram itself, I can only use the first solution.

I will try, as soon as I can, to send a lots of char with the block function and see if it divides, or give me an error, or if it sends all the data and not "respect" the maximum lenght...that can be a problem !