In ControlLogix 5000, the AI module resets the RPI timer each time an RTS transfer occurs. What is the purpose for RPI timer be reset by RTS? If RPI will not be reset, what will happen? If RPI=RTS, RPI timer will expire before reset by RTS, or RPI timer will never expired? If RPI will never expire, does RPI multicast exist? It would be highly appreciated if someone could asnwer this question.