I am using VB to receive data from COM2 and is trying to send this data through a DOS exe file which has be programmed to send data to COM1. This DOS exe file is used to send data with 3964R protocol. For using this DOS file, I need to press 5 , then Input a string, then Enter, and finally press 1 to send the string. The string is the data that I receive from COM2. I just can not use Appactivate and Sendkeystroke to accompolish above action.