Modbus SunSpec is an open, Modbus-based communication protocol that conforms to the SunSpec Alliance standard. The following Fronius products feature interfaces for use with Modbus SunSpec, which enables the easy integration of Fronius inverters into third-party systems via Modbus.
Modbus RTU is available in two different versions (depending on the product):
- Fronius Modbus Card (for Fronius IG Plus and Fronius CL only)
- Fronius Datamanager 2.0 (Box or Card)
Note: the scale factor for calculating the power specification via Modbus has been adjusted in Fronius Datamanager updates to software versions higher than 3.7.1-5. This scale factor is not specified by Fronius – it is stipulated in the SunSpec Alliance specifications. Until now this value has always been 0, but in the new software it is set to -2. This is to facilitate more precise setting of the power specification, in particular for larger systems. This scale factor is to be viewed as an exponent (i.e. the number and direction of comma shifts). A power specification of 100% with a factor of -2 would be written as follows: 10000x10^-2 = 100%. The Modbus value for 100% would therefore be 10,000. To retain compatibility with older Fronius software versions, it is recommended that the scale factor be read correctly via Modbus.
FOR FLOAT QUERY TYPE:
- Register 40243 – WMaxLimPct – power specification value calculated using scale factor (see example above)
- Register 40261 – WMaxLimPct_SF – the corresponding scale factor
FOR INT+SF QUERY TYPE:
- Register 40233 – WMaxLimPct – power specification value calculated using scale factor (see example above)
- Register 40251 – WMaxLimPct_ SF – the corresponding scale factor
Fronius Solar.update/Modbus Card
The Fronius Modbus Card update will bring your card software up to date. You will also receive the SunSpec Inverter Control Model, an additional feature for controlling the inverter using third-party components.