Issue with Power Control Unit 4.1.1 treating first inverter as logger – Modbus RTU on PLCnext 2152

PLCnext Technology & PLCnext Controls
1

Hello everyone,

I’m working on a photovoltaic plant that includes 48 string inverters distributed across three Modbus RTU buses, all connected to a PLCnext 2152 using three RS UNI 1H modules.

For inverter control and monitoring, I’m using Power Control Unit 4.1.1.
For communication with the inverters, I’m using the function blocks:
P_PCUinv_SunSpecAxRsUniLog_2 → PCUinv_SunSpecLog_2.

I’m facing the following issue:
When scanning the Modbus buses, all inverters are detected correctly, but because the library treats the first inverter on each bus as a “logger”, the control commands are not forwarded to the remaining inverters identified on the same bus.

Has anyone encountered this behavior before?
How did you solve it, or do you have any suggestions on how to approach this?

Thanks in advance for any insights.