Node red communication with kepserverx

hello, i'm triying to control a vfd throught plc siemens, i maked the connection with kepserverx and node-red, i'm now able to debug messages, the problem is that i'm not able to apply a function to filter messages, also i want to write into tags that i created from node red to kepserverx

Use/connect a json node after the mqtt-in node. (or change the mqtt-in output to json)

could you please explain, what can i do on the function to just have the "kepsie.siem.retour" message, what can i do to write on the external tags of the kepservex

Follow what Bakman said, then see to get out the part that you need. You can use a change node for that.

Hos about writing back to Kepserver? Do you plan to use MQTT or OPC UA? Tried something already?

NO, im planning to use mqtt, do you have any suggestion

No, not really any suggestions. I have tried both ways a little, but neither really satisfied me. With MQTT you need an additional Kepserver driver license, of course. Fair enough. But I never figured out how to pass status and source time stamp to the OPC tag. Which I needed. Going the other way with OPC UA, I used node-red-contrib-opcua to publish values and created a server with node-opcua for the adress space This was a lot more work and coding but at least kind of solved the tag status handling. This was a year ago and things may have changed.