Excel Macro - Visual Basic - Send command to serial port - Receive Data.

Hello everybody, I know nothing of macros for Excel.
Need of a model that does the following:
Connect to the serial port. (I have completed the model for this)
Send a command.
Receive the answer.
Put received data at X address in spreadsheet.

The RS232 equipment has a button to put the data to excel, but i want to create a button in excel to do the same as the button on the equipment.

Any help will be greatly appreciated. Thank you.