Read/write MQTT tags

Hi there,

I have managed to get my Wago PLC to publish data as sparkplug, to my Ignition. Now they show up in the MQTT Engine. But how can I change write values from Ignition, to the same variables?

By default MQTT Engine is configured to block writes. You can change this on the general tab per this doc: ME: Configuration - MQTT Modules for Ignition 8.x - Confluence

Specifically, you need to uncheck the ‘Block Node Commands’ and ‘Block Device Commands’. This will ensure that MQTT Engine generates CMD messages to the Wago device.

In order for this to work, the Wago device will need to be able to consume these messages and write to the outputs. You may need to get in touch with Wago to see how this is configured on that device.

Thank you! :slight_smile:

So, I’ve now have unchecked both checkboxes. Now, shouldn’t I be able to change this value from here (blue ring) ?


EDIT: Regarding the wago setup I will check with Wago, but for now I’m trying to write back to the broker. (The PLC is not overwriting my change from ignition).

If the Wago device supports you doing that - it will work. When you write a value to that tag in the MQTT Engine provider, MQTT Engine creates MQTT DMCD message and sends it to the Wago device. It is up to the Wago device to write to the output, update the value, and send a DDATA message back to MQTT Engine at which point the MQTT Engine tag will update.

If the Wago device doesn’t support this, it will not update. At this point MQTT Engine is configured to send that message to the Wago device.