This is paper discusses the implement of the close loop control PID block in Safety Instrumented System. PID Block can be implemented by user-defined block. Once the user defined block is created it can be used like normal function blocks like AND, OR, NOT. Here the block is created in Yokogawa safety systems Prosafe-RS. Normally the close loop control block is not used in the safety system so it can be used in non-safety function close loop. The PID blocked is designed by the structured text and the function block diagram language is used.