I need to concatenate several strings - codesys

Question

I am new to stuctured text and I would like to know how to concatenate several string. The cleanest way possible. I this instance I only need to change one variable when creating the string. I have another where I need to do 2. That number will probably grow. The purpose of this is so I can send XML message to an HTTP server. This is for logging data.
In this instance it is the reader variable which is a word.
<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
<s:Header>
<Action s:mustUnderstand="1" xmlns="http://schemas.microsoft.com/ws/2005/05/addressing/none">http://tempuri.org/IService/receiveHeartbeat</Action>
</s:Header>
<s:Body>
<receiveHeartbeat xmlns="http://tempuri.org/">
<reader>**Word Variable**</reader>
</receiveHeartbeat>
</s:Body>
</s:Envelope>

Answer 1

You can chain CONCAT functions like so:
concat3: STRING := CONCAT(CONCAT(str1, str2), str3);
However, beware that by default STRING is only 80 characters (bytes) long. You can specify the size using parenthesis:
concat3: STRING(255) := CONCAT(CONCAT(str1, str2), str3);
But again, the standard CONCAT function only accepts and returns strings of up to 255 in length!
If you need strings longer than 255, then check Working with Strings More Than 255 Characters in the codesys documentation

Answer 2

If you are using Wago then you should have access to their CONCAT functions...CONCAT3(),CONCAT4()...CONCAT9(). This is much cleaner than nesting a lot of the standard CONCAT funct

Answer 3

I take it that you need to do this in JavaScript.
var replaceDue = "<s:Envelope xmlns:s=\"http://schemas.xmlsoap.org/soap/envelope/\">\
<s:Header>\
<Action s:mustUnderstand=\"1\"xmlns=\"http://schemas.microsoft.com/ws/2005/05/addressing/none\">http://tempuri.org/IService/receiveHeartbeat</Action>\
</s:Header>\
<s:Body>\
<receiveHeartbeat xmlns=\"http://tempuri.org/\">\
<reader>**Word Variable**</reader>\
</receiveHeartbeat>\
</s:Body>\
</s:Envelope>";
var wordVariable = "value to replace";
var replaceDone = replaceDue.replace("**Word Variable**", wordVariable);

Answer 4

I think I have found a solution. I don't like it though. It's not very clean.
Reader_ID: STRING := '0';
msg: STRING(500);
Msg1: STRING(250) := '<s:Envelope xmlns:S="http://schemas.xmlsoap.org/soap/envelope/"><s:Header>';
Msg2: STRING(250) := '<Action s:mustUnderstand="1" xmlns="http://schemas.microsoft.com/ws/2005/05/addressing/none">http://tempuri.org/IService/receiveHeartbeat</Action>';
Msg3: STRING := '</s:Header><s:Body><receiveHeartbeat xmlns="http://tempuri.org/"><reader>';
MsgAfter: STRING := '</reader></receiveHeartbeat></s:Body></s:Envelope>';
msg := CONCAT(Msg1,Msg2);
msg := CONCAT(msg,Msg3);
msg := CONCAT(msg,Reader_ID);
msg := CONCAT(msg,MsgAfter);
It seems that string sizes are limited to 500 characters. Since the point of this is to create an XML message to send via HTTP. What happens when my messages inevitably get larger than 500 character. I am using the WagoLibHttp_02 library for http.