There have been multiple topics here about SMA but none really described with step by step instructions how to get such data.

I have discovered using multiple Modbus test software on my Windows machine and iPad (iOS)  that although SMA supports Modbus TCP I still need to enter the correct Unit ID of the SMA to get any data.
So it is actually Modbus RTU packed in TCP/IP header.

If I change the Unit ID in SMA I also have to change the Unit ID in Modbus Poll for example to get data. Read registers using Unit ID 0 or 255 never works.

Now I am getting to the Logo settings:

I think the settings for Modbus should be fine now but still do not get any data in my project.
I guess I use the wrong function block.

With Network input I can select Variable Memory (VW0 for example) but this is only 1 byte but I need to collect the data from 4 bytes (32 bit data stored in VW0,1,2,3) but how do I do that ?

I do not need any Float/Integer conversion so how do I read this 4 bytes of data (from 2 combined Modbus registers) as a real value in my program ? 

In relation to the above I did some testing and depending on the reading format the actual value will be available in register 30771 or 30772.

In binary it is clear only the 16 lower (LSB) bits are used and the upper MSB bits are all 0.

In more advanced "bit-sorting" options we can have multiple choices defining how the data is presented.

I guess the Logo can only do Signed or Unsigned so the data is in register 30772 but when you can select "Big-endian" format the value is presented in register 30771.

I am not sure what is supported by Logo or not ...   

ixo65, thank you .. I will try that.

And yes, it is DC voltage with 2 decimals.

See enclosed SMA Modbus manual.
I set the NI to read VW2.

Some additional notes:

You mention that 16 bit is +/-32767 (= signed16)  which suggests I can only read up to 327,67 Volt.

Is there a way to use it as U16 -> 0-65535 ?  --> up to 655,35 Volt ?

I still get no data, tried to read 30777 as this reads a value always below 1.000 (Watts per phase) so no risk of overflow of value 32767. Still no data ...

Is there an alternative way to see if there is any data in variable memory at all ?
Could be still that the Modbus connection is not getting the required data and we are now fighting with the function blocks :-(

Yes !! ... Finally :-) .... thank you very much.

It is confusing as you need to address 30777 in the other tools and then SMA replies with 2 registers 30777 and 30778.

Requesting register 30778 direct I did not get the correct data, see picture with the several options.
Apparantly the Logo works a little different.