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SunSpec communication protocol in UniStream


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Hello everyone.

At this moment I'm in the middle of a big project that involve the unistream HMI+PLC that we use and a SunSpec communication protocol from one of our solar generators system vendor, I've been looking allover the internet to find any example, but there is no past develop with this characteristics, I've anybody can give me a hint I appreciated.




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thanks for your answer... maybe I didn’t explain my self correctly, I have some knowledge about MODBUS RTU, and I know that MODBUS TCP is not that different from the RTU, yo just have to add de IP address, the TCP port and the slave or master ID, so far, I got that, but sunscpec uses a DID identifier, and some other addressing method that have become really confusing.

As you can see in the picture there is a little piece of the tables, but when you try to setup the addressing from one block to the other there is no way to do it...

according to MODBUS standards it supposed to be only one table with many memory addresses to call each parameter, but in this case I don’t find the way to uses more than one table.

the sunspec is a standard communication protocol with addressing assignation, but it also have a different communication string, and that the part that blocks me.

If you can give me a hand I appreciated



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  • MVP 2023

According to the document this is Modbus.  As you've mentioned, Modbus does not provide a provision for DID.

I would ignore the DID value for Modbus communications.  You need to have one of these handy to do some testing with a PC before you try getting the PLC to talk to it.  I would locate a freeware Modbus TCP master program and try to read data out of it using the Start address in the table.  

Of course, you could always call the manufacturer.

Joe T.

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Hello Joe.
We, ve been doing some research apparently the SunSpec Modbus protocol is not modbus, it just uses the tcp port from modbus and the same hardware, after that it is a whole new protocol with long strings of data that needs to be manage block by block, according to our research there is no PLC with SunSpec protocol implemented.

If you find any new information we appreciated.


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