Modbus RTU comunication

Hi all!
This may be a simple answer from many in the forum, but for me its been a struggle.

I’m able to send a request in the format of serial of 8bytes data. hence query to a RTU device.
in return the device responds via serial with 13bytes.
I can sort of read the bytes via:

if (Serial.available() > 0) {

incomingByte = Serial.read();

lcd.setCursor(1, 1); ( external I2C screen)

lcd.print(incomingByte);
}

The Question is, How can I save the 13 bytes received in order to be used later.
this is the request:
11,03,00,54,00,04,07,49

this is the response:
11,03,08,00,64,00,3E,00,0D,00,55,9C,E8