Check thqt Serial coms are working

Projects Networking, Protocols, and Devices
5 
 dave = Serial.read();
 lcd.clear();
 lcd.print(dave);

This won't work, as it reads and prints a single character.

It appears that you have two options for data return, ASCII floating point and binary mode. In binary mode, the device sends back 4 bytes that make up a (binary form) floating point number.
From the data sheet:

$Rxx? Read data (float or int) from register xx ex. +2.000e+01

$RNxx? Read float data in IEEE754 type from register xx ex. A1A8FCBA

In either case, you need to read several bytes and combine them to form the result.