CHOO

Hi Everyone, I am new to PLC , hope can get help from the below requirement. I have project need to send message from pc to PLC via TCP IP and i am using VB.net programming. 1. I have write program to receive data from PLC is working. PC will send back the message when receive the data from PLC and PLC able to received too. 2. I have another program need to send the message from PC to PLC by IP Address and port but every time i connect will get the error message not reachable for destination port. I check with the PLC supplier they say the Port no already open for listening the incoming data. My objective is to send a message to PLC to do some action after complete PLC will send back the complete status. If able to provide coding example is much appreciated. Regards Choo