root@raspberrypi:/home/pi/esptool/esptool# ./esptool.py --port /dev/ttyS0 --baud 115200 --chip esp8266 read_flash 0x00000 0x400000 ~/growatt.3.0.0.2.bin
esptool.py v4.3-dev
Serial port /dev/ttyS0
Connecting...
Failed to get PID of a device on /dev/ttyS0, using standard reset sequence.
Chip is...