General Procedure to Writeback to PLC

Hi there,

We currently have MQTT Architecture in place for Igntion, we utilize CMT-G01 Maple system gateways to pull read all the tags via MQTT to Ignition.

I would like to experiment writing back to PLC Tags. PLC we use is AB Compact logix.

I am not sure how to achieve this. Can someone please help me with step by step guide? I tried writing back to MQTT Engine tags but says read only, even if disabled all blockings.

Thanks

Are these gateways publishing to MQTT in Sparkplug format or have you used a custom namespace instead?

we have a custom namespace.

With a custom namespace tags are read only and you can only publish back to it via system.cirruslink.engine.publish

https://docs.chariot.io/display/CLD80/ME%3A+Python+Scripting#ME:PythonScripting-publish

so from what I am understanding, I need to publish topic to MQTT engine and have the CMT-G01 subscribe to that topic? If so, how does CMT-G01 will write back to PLC? Will that be topic subscriber?
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Sorry, I don't know anything about your CMT-G01 device. Presumably yes, it would need to be subscribed to the topic you published to, and have some ability to then write back to the PLC.

Sounds good. I will experiment this and give review, Thank you!

Great news I can see that the topic subscriber received the topic! thank you!