Internet PLC Forum

I am new to PLC programming. I had some old PLCs lying around in our lab and i wanted to learn to program using these PLCs. Now the problem i am facing is in loading program or trying to connect to PLC. Whenever i try to connect to PLC it asks for a password which no one here knows as these have not been used for some time now. I went through some old threads relating this problem. And i tried sending command IR* but it replies with PWER* instead of IR01* or something like that. Can you tell me the problem or what can i do to solve this issue?