ActiveMQ Acknowledging Messages correctly on QOS1 from Siemens PLC but never putting them in the topic.

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Devlin Paddock

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Aug 15, 2019, 10:55:43 AM8/15/19
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Hey so this may not be the best forum for this but i couldnt find a better one.
I am having a problem connecting with the ActiveMQ broker over MQTT from a siemens 1500 plc. I have tested the Broker with a c# application and it seems to respond fine and publishes requested messages correctly.
So the problem i am having is when attempting to publish from a Siemens plc the following occurs
PLC sends out (32 71 00 0B 53 4E 50 2E 49 6E 62 6F 75 6E 64 00 11 01 03 01 7B 22 4D 61 63 68 69 6E 65 22 3A 22 48 49 4C 2D 58 53 2D 46 49 4D 22 2C 22 47 6F 6F 64 22 3A 22 30 22 2C 22 42 61 64 22 3A 22 30 22 2C 22 41 74 74 65 6D 70 74 22 3A 22 31 22 2C 22 45 6D 70 74 79 22 3A 22 30 22 2C 22 4F 74 68 65 72 22 3A 22 30 22 2C 22 48 65 61 64 22 3A 22 31 22 7D 20) in hex or (2q SNP.Inbound {"Machine":"HIL-XS-FIM","Good":"0","Bad":"0","Attempt":"1","Empty":"0","Other":"0","Head":"1"} ) in ascii.
This packet i went through seems to be in good format.
ActiveMQ Responds with(40 02 00 11) Hex ( puback for packet 11)
However this packet never appears in the Topic SNP.Inbound.
Im not sure what im missing here especially since ActiveMQ is acknowledging the packets i was wondering if maybe i was missing something in my packet generation ?
I am currently unable to enable logging on the ActiveMQ server as those here before me didnt open it up to JMX and im unable to take the factory down to reset the server...
Thank you for any help you can offer in advance.

Alexander Kaiser

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Aug 20, 2019, 6:36:15 AM8/20/19
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Hey Devlin,

not sure if this might help as currently, I don't have ActiveMQ to test. But your topic name SNP.Inbound might be problematic with MQTT.
The MQTT Specification does neither permit nor forbids the dot. However, it won't interpret this one as a separator as ActiveMQ might be used to.

Good luck and best regards.

Devlin Paddock

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Aug 20, 2019, 7:09:49 AM8/20/19
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holy dear god i love you. ActiveMQ Converts all .'s to / and all /'s to dots. I couldn't enable logging on activeMQ to see what it received but you led me down a rabbit hole that found the problem

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