TRB145 Data to server: does it implement a queue?

NETWORKING SOLUTIONS
1

Hello,

My setup is the following:

  • A TRB145 is collecting data from an electrical meter using Modbus RTU,
  • Data is collected every 60 seconds, using Modbus Serial Cient service,
  • The “Data to server” is set up in the following way:
    Server type: HTTP
    Period: 60
    Retry: on
    Retry count: 2
    Timeout: 1
    Server address: x.x.x.x:1880/send
    (data is received by node-red)

My question is rather simple: does this configuration implement a queue? For example if the mobile data connection is down for let’s say an hour, is the data queued? When the mobile data connection is up again, will all remaining data sent (with its own original timestamps)?

I have made some tests and it seems that the answer is yes, but could someone from Teltonika confirm that this is the required behaviour? (I have seen that collected data is stored in an sqlite database file at /tmp/modbus_db and there is a table called sent_id_table in this database that I suppose is for this functionality).

If the answer is yes, how big is this queue? Of course this is rather hard to answer, because it surely depends on how big is the requested payload. But an approximation would be wellcome!

Thanks,

Gabor

3

Hello,

Yes, you are correct. When there is a mobile connection loss, the Modbus serial client’s collected data is indeed cached in the database you mentioned. Once the connection is re-established, the stored data is sent to the server with its original timestamps intact.

As for the queue size, the approximate maximum amount of data that can be cached in this database is around 1.2 MB.

Please feel free to reach out if you have any additional questions.

Best Regards,

4

Hello,

Many thanks for your answer.

I still have a question: I tried the same configuration, but with MQTT communication instead of HTTP. With MQTT there seems to be a bug; there are many times that the same data is sent over and over (it seems that the “sendig is okay” machanism does not work with MQTT). Is this a bug, or do I do something wrong?

Regards,

Gabor

5

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