I have a task to do functional testing of RS485 interface to a microcontroller CPU. Does anyone know any examples or anything that can help me understand the task, i.e. what needs to be done. Kindly do help me. Thank You.
Is it 485 Modbus or just Serial?
Is there a manual/datasheet that comes with the CPU?
When you say functional testing, what exactly do you mean? If I had to guess, there's a list of functions available to you and you need to write a program that mimics something.
Use an RS-485 controller that shows up as a COM port. Then you can just use VISA to send and receive commands and data. We would need to know the command structure for the communication bus in order to give any real help, but you could start here: VIWeek 2020/Proper way to communicate over serial
It is RS485 Modbus
In that case, open up VI Package Manager and install the NI Modbus Library. Use it to read and write all of the registers.
Maybe an idea to test stability, by putting a variable resistor to send and receive to see at what voltage level the system breaks down. It is not the functional testing, but gives an idea about how long your cabling is acceptable.
But first make it work as crossrulz said.