Why are the tag values invalid or why is the tag server not reachable?

If a tag has an invalid value (see screenshot below) or if the tag server is not reachable, please ensure the following:

Please note:

With a mouse-click on the red exclamanation mark you can see more information.
  • The connected component must be reachable from the mbNET. You can ensure this with a ping-request on the device web interface under "Advanced" ~> "Status" ~> "Diagnostic" ~> "Ping":
You can enter there IP addresses and domains. In this example, the IP address of the component is "".
  • In the configuration of the component the access via PUT/GET-communication through distant partner (PLC, HMI, OPC, ...) must be allowed. At a Siemens® component you must configure this under "General" -> "Protection" -> "Connection mechanism" in the TIA® portal:

  • Furthermore, the configured "Port" / "Slot" / "Rack"  at the tag server must accord with the PLC configuration:


Please note:

If needed, you can select the type "ModbusTCP" as the tag server. But this depends on your component, what is possible.

The tag server is in the mbNET integrated. So, the mbNET acts as a Master in this case.
Typ: FAQ Revision: EN-mbconnect24-06-V1.0 Datum: 28.02.2018