Despite your best efforts, you may encounter an outdated or missing manual. Here is what to do:
See Group PC parameter settings. 9.2 Communication Modes. 9.2.1 The protocol is Modbus protocol. Besides the common register Read/ CHE100 Inverter User Manual PDF - Scribd
Per manual: Set P0-16 = 1 (reset to default). Note: This clears all custom parameters.