Product Overview; Modbus Protocol; Sma Modbus Profile; System Topology - SMA Modbus EDMM-US-10 Technical Information

3 Product Overview

3 Product Overview
3.1

Modbus Protocol

The Modbus Application Protocol is an industrial communication protocol that is currently used in
the solar sector mainly for PV system communication. The Modbus protocol has been developed for
reading data from or writing data to clearly defined data areas. The Modbus specification does not
prescribe what data is within which data area. The data areas must be defined device-specifically
in Modbus profiles. With knowledge of the device-specific Modbus profile, a Modbus client (e.g. a
SCADA system) can access the data of a Modbus server (e.g. SMA product with Modbus
interface).
The SMA Modbus profile and SunSpec Modbus profile are used for SMA products.
3.2 SMA Modbus Profile
The SMA Modbus profile contains definitions for SMA products. All available data on SMA
products was assigned to the corresponding Modbus registers for the definition. Not all SMA
products support all Modbus registers of the SMA Modbus profile.
For supported Modbus register (see Section 4, page 15).
3.3

System Topology

An SMA product with Modbus interface is connected with the SCADA system of the electric utility
company or the grid operator via Ethernet. The Modbus interface also enables communication via
the Modbus protocol. From the perspective of the Modbus protocol, an SMA product with Modbus
interface constitutes a Modbus server that supports the SMA Modbus profile.
3.4

Addressing and Data Transmission

3.4.1

Unit IDs

The Unit ID is a superordinate addressing type in the Modbus protocol.
The following tables shows the Unit IDs supported by this SMA product.
Unit ID
1
2
3.4.2

Register Address, Register Width and Data Block

A Modbus register is 16 bits wide. For wider data items, connected Modbus registers are used and
considered as data blocks. The address of the first Modbus register in a data block is the start
address of the data block.
8 EDMM-10-Modbus-TI-en-11
Explanation
This Unit ID is reserved for information on the SMA product.
This unit ID is reserved for the system parameters and measured val-
ues.
SMA Solar Technology AG
Technical Information