Hi, My Thesis mainly on PLC and my job is to contorl the positon of the Pneumatics by Festo plc only. Morever, i have to use festo plc but it's not give freedom to use. Lots of restriction in festo plc. So, even in worst case, the plc expert in company, suggest me to use c programming. I think when programe too lengthy, i will use C programming. Yes, PC time run application i want to use or call in plc programming. So, i want to call C programme in festo plc? Thanks for quick reply. And yes, dont take me in wrong way. I am new to this forum. Once again thanks. Regards, Abhi