Fallback driver used when a slave is named without a specific hardware driver.
When used with process_data: {:all, domain_id}, this driver auto-discovers
all PDOs declared in SII EEPROM and registers one signal per PDO. Signal names
are derived from the PDO index: 0x1A00 → :pdo_0x1a00.
Raw bytes are passed through unchanged for both encode and decode, so
read_input/2 returns a binary and write_output/2 accepts a binary.