With Just One Click: Questions and Answers on Modbus

If you want to use your own monitoring, Scada or data logging system to manage operation of your PV system, you can simply integrate the inverters via the Modbus interface. For more than two years, SMA has been equipping all inverters with this standard interface, offering straightforward solutions to third providers, in particular, who want to provide system operators with their own, non-SMA system.

SMA employee Falko Schmidt answered all questions on Modbus

Falko Schmidt gathered and answered all questions on Modbus asked by coustomers

SMA employee Falko Schmidt has set himself the task of gathering and answering those questions on Modbus most frequently asked by customers.

And to make the approximately 30 questions and respective answers already gathered available to those who have similar questions on Modbus, Falko summarized them in a detailed FAQ catalog. This catalog is available at SMA Developer, a website for developers where all development documentation of SMA products can be found.

Have fun browsing the blog.


Have a look at the SMA Developer (please select “FAQ Modbus”)

  1. Avatar
    Cuan Boake says:

    I am integrating a multicluster (6 x SI 8.0H) via a cluster controller into a SCADA system using Modbus and have the following problems:

    1. Reading input registers : the reaction time from when a parameter changes on the Sunny Remote Control to when the Modbus register updates is very slow (more than 1 minute, sometimes 2-3 minutes).
    2. If I change a parameter using the holding registers they do not update on the inverter – I can read the holding registers ok via the correct Unit ID. (For eg – generator start battery SOC).

    I have tried to ring SMA service centre but there is no English support at the communications help desk.

    Thank you

  2. Avatar
    Mohamed Ashraf says:

    Dear Attandee

    i would like to know the mod bus communication between fuel save Controller and Gen set .
    Kindly explain the following
    1. is it possible all genset or will it require any interface ?
    2. what will be the minimum Genet requirement to do so


    • Christian Höhle
      Christian Höhle says:

      Dear Ashraf,

      the Fuel Save Controller offers different ways to use gensets in Hybrid Systems:

      1) If the gensets are equipped with a compatible genset controller, the FSC can directly communicate with these genset controllers (please see “Use of Gensets in PV Diesel Hybrid Systems withSMA Fuel Save Controller 2.0”).

      2) If the genset controller in use is not compatible, the genset controller manufacturer can add Fuel Save Controller Support by supporting the SMA Fuel Save Controller’s generic genset protocol.

      3) If the genset controller does not meet (1) or (2), or gensets are manually operated, the FSC can measure the genset’s power output to control the solar energy accordingly.

      With these 3 options, the FSC is able to integrate nearly any genset system into a hybrid grid.

      Sunny Regards,

  3. Avatar
    Lars Inge Leirflåt says:

    We have set up the speedwire network to be on the same network as the external network, turning of DHCP. And setting fixed IP addresses to each component there (three Sunny Island 4.4M-12, three Sunny Tripower and a cluster controller – using speedwire).

    All the components are online and ok in the clustercontroller, but I cannot communicate with the sunny island from the external network. It still doesn’t route packages from external to speedwire.

    Modbus server has been activated in the sunny island.

    Connecting PC to speedwire nw, I manage to connect to SI through Modbus, but it only register that is readable is 30055 stating that it is an SMA device. However I get answeres from registers 40149-153, where I only got timeout when trying through the CC.

    Attached is screenshots of network settings, and Modbus queries when connected with pc on speedwire nw.

  4. Avatar
    Edgar Bueno says:

    I have an installation with three sunny island SI5048 connected to a webbox. I am trying to get moddbus communication through a webbox. I am using Labview OPC modbus server. But I am not able to get communication. Are there some one who has used modbus with a webbbox, that can help us?
    Thank you


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