Receivin long TCP messages

Hello,

  I am using fbRecvFrom for receiving text messages with length around 1000 Bytes. The messages are not delimited with any symbol, so I cannot use fbRecvTxt or fbRecvChar. Unfortunately, I cannot use STRING variable for message reception as the STRING length is limited to 255 character. I can use ARRAY[1..1024] OF BYTE for receiving the message, but I am not able to convert it to STRING. Could you write me short snippet how it can be solved?

 Even when I use STRING for shorter messages and then try to trim its length to length of received data, the result trimmed string is empty. For some strange reason the output variable of fbRecvFrom keeps  to be zero. So the LEFT function correctly returns empty string:

  VAR_OUTPUT
    receivedData : STRING[255];
    receivedDataString : STRING;
  END_VAR
  VAR
    lastErrorCode : USINT;
    receivedDataLength : UINT;
  END_VAR

gRecvFrom( rq := true, chanCode := ETH1_UNI0,
          lenRx := 255, data := void(receivedData),
          error => lastErrorCode, lenData => receivedDataLength);
receivedDataString := LEFT(receivedData, receivedDataLength);

By the way, I recently found that there are a lot of troubles with receiving telegrams if you create more than one instance of fbRecvFrom for the same communication channel in your PLC. You have to create only one global variable instance for each channel and use it. Otherwise you may "receive" the same message from each instance. Well, when you consider the basis of TCP channel as a shared resource, then this behavior probably makes sense. But you should note it in the documentation I think.