# RUT956 missing MQTT fields

**URL:** <https://community.teltonika.lt/t/rut956-missing-mqtt-fields/21478>\
**Category:** Issue\
**Created:** [October 8, 2026, 11:48am UTC](https://community.teltonika.lt/t/rut956-missing-mqtt-fields/21478 "2026-10-08T11:48:06Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Linux-RISC](https://community.teltonika.lt/letter_avatar_proxy/v4/letter/l/aeb1de/32.png) [@Linux-RISC](https://community.teltonika.lt/u/Linux-RISC)\
**Post date:** [October 8, 2026, 11:48am UTC](https://community.teltonika.lt/t/rut956-missing-mqtt-fields/21478/1 "2026-10-08T11:48:06Z")

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I’m reading several MODBUS variables from 4 devices every 10 seconds with no errors.

 ![image](https://community.teltonika.lt/uploads/default/original/3X/d/4/d4a6eac64fd9d5f3944178293ba8fa017873574c.png)

I’m sending these variables to a MQTT server every 60 seconds but, for unknown reasons, some routers (same model) avoid some fields just sometimes:

 ![image](https://community.teltonika.lt/uploads/default/original/3X/4/f/4fed8f143a589e1d8923003ba88198e9b319ab82.png)

 ![image](https://community.teltonika.lt/uploads/default/original/3X/7/7/7799e6bf8cd86febb82e45ac4c5e9f2b96b7e271.png)

Complete message:

[{“V\_l1”:“2431”,“date”:“08/10/2026 13:22:48”},{“V\_l2”:“2379”,“date”:“08/10/2026 13:22:48”},{“V\_l3”:“2354”,“date”:“08/10/2026 13:22:48”},{“I\_l1”:“0”,“date”:“08/10/2026 13:22:48”},{“I\_l2”:“100”,“date”:“08/10/2026 13:22:50”},{“I\_l3”:“0”,“date”:“08/10/2026 13:22:52”},{“activePower”:“0”,“date”:“08/10/2026 13:22:54”},{“activeEnergy”:“3313”,“date”:“08/10/2026 13:22:56”}]

The MQTT server sometimes receives messages with missing fields:

[{“I\_l1”:“0”,“date”:“08/10/2026 13:18:10”},{“I\_l2”:“0”,“date”:“08/10/2026 13:18:12”},{“I\_l3”:“0”,“date”:“08/10/2026 13:18:14”},{“activePower”:“0”,“date”:“08/10/2026 13:18:17”}]

[{“activeEnergy”:“7”,“date”:“08/10/2026 13:19:09”},{“V\_l1”:“2319”,“date”:“08/10/2026 13:19:11”},{“V\_l2”:“2286”,“date”:“08/10/2026 13:19:13”},{“V\_l3”:“2333”,“date”:“08/10/2026 13:19:15”},{“I\_l1”:“0”,“date”:“08/10/2026 13:19:17”}]

How can I avoid this strange problem? Is there any recommendation about MODBUS vs MQTT period?

Thanks in advance.

Edit: it looks that these messages contain the tail of the previous message and the head of the next message.

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<div class="post-metadata">

**Author:** ![Linux-RISC](https://community.teltonika.lt/letter_avatar_proxy/v4/letter/l/aeb1de/32.png) [@Linux-RISC](https://community.teltonika.lt/u/Linux-RISC)\
**Post date:** [October 11, 2026, 2:04pm UTC](https://community.teltonika.lt/t/rut956-missing-mqtt-fields/21478/3 "2026-10-11T14:04:35Z")

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I’m reading several MODBUS variables from 4 devices, I’ve checked that when one of the devices is off, the problem arises.

I can also state that if you’re reading 4 MODBUS variables and one of them is an illegal address, the variable is avoided in the MQTT message and the 4th variable in the MQTT message will be the fist MODBUS variable read.