Help with IPC CFX, convert MQTT to AMQP from PLC

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Eric C

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May 14, 2021, 12:04:45 PM5/14/21

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I'm a noob when it comes to this messaging stuff, and need to CFX (connected factory exchange) data in AMQP from a Siemens PLC (S7-1500) and I don't even know where to start.

There doesn't appear to be a way to send AMQP from the PLC but it is possible to send MQTT from the PLC. So I was wondering if a PC with RabbitMQ can capture MQTT and send it out as AMQP encoded in JSON?

It would be great if there's a box that can do all of this and all I need is to configure it. Any info or help would be great.

Thanks!

Hans-Martin Mosner

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May 15, 2021, 1:25:43 AM5/15/21

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RabbitMQ does have a MQTT plugin, so it should be possible to connect an MQTT client to a RabbitMQ broker after just enabling the plugin.

However, RabbitMQ doesn't involve itself with the content and format of messages, so AMQP clients will see the messages injected by the MQTT client just as they are, and if the PLC doesn't send JSON data, consumers won't see JSON data.

You will have to write some intermediate process which receives messages from the PLC, translates them into a suitable format, and retransmits them for the JSON-expecting consumers to process. For that, you need to know the format of the PLC messages. Writing the translator in python for example should be a piece of cake.

If the consumers are under your control, you can of course extend them to understand the MQTT messages from the PLC.