We have an old HMI of CP 435T(without ETH) with an old program running. Now I need to upload the project from the HMI to my PC. So I have used Com1 and selected Configure the communication from the CP400Soft as DIP switch 5 is OFF...But while trying to upload it shows failed to open the Com port. I have checked the communication parameters and it is fine. I am using RS485 for communication.