Compiling this sketch uses a lot of RAM:
Using library ArduinoRS485 at version 1.0.0 in folder: C:\Users\Donald\Documents\Arduino\libraries\ArduinoRS485
Using library ArduinoModbus at version 1.0.3 in folder: C:\Users\Donald\Documents\Arduino\libraries\ArduinoModbus
"C:\Users\Donald\AppData\Local\Arduino15\packages\arduino\tools\avr-gcc\7.3.0-atmel3.6.1-arduino7/bin/avr-size" -A "C:\Users\Donald\AppData\Local\Temp\arduino_build_88235/ModbusRTUClientKitchenSink.ino.elf"
Sketch uses 17588 bytes (57%) of program storage space. Maximum is 30720 bytes.
Global variables use 1823 bytes (89%) of dynamic memory, leaving 225 bytes for local variables. Maximum is 2048 bytes.
Low memory available, stability problems may occur.
Is this correct ??
Board = Arduino Nano