PLC to RPC XML v3.02

Industrial
1

I am new to node red and having trouble finding where to look for an example.

I have an S7-1200 Siemens PLC hooked up to a barcode scanner.

I need to take some values off the PLC (which I have done already and am able to see values) and send them to a RPC api formatted in XML.

I have the structured XML ready but I am not sure how to format it so I can input variables from the PLC. I have a "template" but not sure if I am doing it correctly.

My trials so far:
S7-In -> Template (not sure how to function it here) -> XMLRPC
S7-In -> Function -> XMLRPC

The tutorials I have seen basically say structure for JSON and use XML parser, is that the best way?

Appreciate any help my Google Fu is failing me.

2

It is "a" way.

If the XML structure is static then a template can be easier.

What do you mean by "not sure how to function it here"?

The built in help of the template node provides a basic how to (and provides the mustache syntax) e.g...

Suppose you get data from PLC, then "condition it" in a change node or function node so that going into the template node is the following msg...

{
  topic: "widgets",
  payload: {
    name: "Recipe 1",
    speed: 400,
    pressure: 5.5,
    holdTime: 2500,
    coolTime: 4000
}

but you need the final XML format of ...

<?xml version="1.0" encoding="UTF-8" ?>
<root>
  <name>widgets</name>
  <recipe>
    <speed>400</speed>
    <pressure>5.5</pressure>
    <hold-time>2500</hold-time>
    <cool-time>4000</cool-time>
  </recipe>
</root>

you could achieve it with the template ...

<?xml version="1.0" encoding="UTF-8" ?>
<root>
  <name>{{topic}}</name>
  <recipe>
    <speed>{{payload.speed}}</speed>
    <pressure>{{payload.pressure}}</pressure>
    <hold-time>{{payload.holdTime}}</hold-time>
    <cool-time>{{payload.coolTime}}</cool-time>
  </recipe>
</root>
3

Steve,
Thank you. Exactly an example I was looking for that should give me everything I need to get this done. Funny I saw a similar question earlier 2-3 years ago you answered didn't expect to see you here but thankful nonetheless, appreciate the help!

4

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