SMA Modbus TCP/IP warnings/fails

Dear all,
I am reading from SMA via Modbus TCP/IP 3 values per 1 min every 4 min. It fails approx 4 - 6 times per 24 hours with the following errors:
15 Dec 04:06:20 - [warn] [modbus-getter:modbusGetSolarkWh] FSM Reset On State QUEUEING
15 Dec 04:06:44 - [warn] [modbus-getter:modbusGetSolarkWh] FSM Reset On State INIT

Anyone having any idea what to do, I do want too avoid loosing the data for the requested read as much as possible.

does it always concerns the same register?
I see in the modbus spec from SMA that the Wh registers has a lenght of 4 instead of 2 like the others

I am reading the following 3 items from SMA:

  • Acccumulated kWh production
  • Momentary W
  • Time
    In almost all cases one or both of the first 2 are the items that fail, rare that the Time fails but has happen

Are you triggering multiple read requests at the same time, or doing them one after the other. If at the same time then try spacing them out so they do not overlap. Even better is to do them in one read, if the addresses are not far apart.

The adress's are to far away, the spacing is 20 sec between each read in the minute when I am reading.

Do you think 20 sec should be sufficent spacing, OR is the SMA Modbus Server so slow in reply that it could overlap even with 20 sec?

Sorry, I don't know about that, presumably you can tell from when the messages are received whether that is the case.

SMA has a max. number of pollings per day or something... unfortunately I can't find the excat value now

not sure if is good to poll every 20sec a different register. Why not read every register in one step?

I use node-red-contrib-modbustcp
poll every 25s 3 registers with modbustcp-read and it is working fine


from SMA-Modbus-general

Data Transfer Interval via the Modbus protocol
For system stability reasons, the time period between data transfers via the Modbus protocol must
be at least ten seconds. No more than five parameters and measured values should be transmitted
per SMA inverter.

sounds enought from SMA-side :roll_eyes:

i query every 5s my 4 SMA inverters since years without problem, In addition, a charging station (called openWB) query the 4 inverters via modbus every few seconds too.

I could query every 2s if I want.

You can check my flow(s): 10.12.2021 - Google Drive

This is my setup and the given alarms, Can I get help by someone to get explained the serial with alarms that I sometime get?
The communication is over Internet and I get 4-5 errors a day (not including what I believe is errors that follows the initial error).
I tried to move the requests to be 40 sec between and asking for one value at a time from the SMA Solar Inverter.
Is there anything I could try out to change to improve and reduce the errors?
I have also S7 communication to 2 different PLC's that hardly never fails or give errors.
Also the S/ communication is spread out to not have a chance to conflict the time when the Modbus requests will occour.
Would be very greateful for inputs, help

This is the Modbus setup I am using as referense to support if someone could explain the behaviour of the errors, based on setup and error timestamps given in earlier attachments

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