Hi Marco, What you are seeing looks less like a coding mistake and more like a limitation or bug in the FBD editor parser when handling VAR_GENERIC CONSTANT specializations. The fact that the same FB works correctly in ST and only fails when instantiated on the FBD canvas strongly suggests that the graphical editor is not resolving the generic parameterized type correctly. One thing I would try is creating a non-generic wrapper FB around your specialized instance and exposing the required methods...
Hi — good description of the problem. A few suggestions / questions that might help narrow this down: Since your first serial port (COM2) works fine but the second (COM4 + MODBUS_EXT_MASTER) never opens, check whether the two ports are truly independent — some WAGO modules share internal resources, so COM4 might conflict with other functions or modules. Make sure that the physical wiring and module configuration for the second port (baud rate, flow control, RS-485 vs RS-422, etc.) exactly match what...