Max packet length (L=F6 gives 255 byte including header) is supported, but you need to increase the UART baudrate >= 56700 baud. For N mode using low RF Data Rate the module will not complete the packet transmission before internal timeout (default 2 second) takes place. Increasing UART baudrate ensure that the module have time to complete the packet TX before timeout.
Last Update: November 9, 2017
November 9, 2017 1217 Wireless M-Bus Q&A