Write back to same MQTT tag

Maker
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1

Hello,

Using MQTT engine i get all my tags easily. But i want to be able to write back to the same tag. Is it possible to do that? If so, how can I do that? It says that the tag is read-only.

2

If these are coming from SparkplugB, then you should be able to just enable outbound writes in the MQTT Engine settings (they are disabled by default). If it is a custom namespace and plain MQTT topics, then I believe you have to do those via scripting functions such as system.cirruslink.engine.publish.

1 Like
3

Thanks. I want to learn about sparkplug, and how its done in the industry. Is it normal that i.e PLC publish its current setpoint, and that Ignition write back to the same tag, if I want to change the value? Or is there another practical way of doing this?

Also, when I try writing back, it automatically gets overwritten as you see below... :confused:

image

image

I have enabled outbound tag write also
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Any ideas?