Read bytes at serial port direct and in-direct

Hello,

I have questions regarding write-read operation from a serial port.

I have an instrument with message based communication. I prepared a simple VI to send command and read the response. (I disable the default termination character and appends EOL to the command format).  I prepared three versions:

In the first I determine myself the expected bytes to read (in the attached image I read the temperature of the device).

This works and I get an answer quickly - but I want to process to be more general so it will suite for different number of byte for example - serial number readout.