What is the mechanism the HMI captures a plant-event?. Some context below:
1.- a dry contact provides a digital input to the RTU. I guess this RTU or PLC keeps monitoring its inputs by using a close loop like:
2.- once the PLC /RTU capture a data then it is sent via protocol to the HMI-DATABASE which stablishes communication and receives the new data base (updated) from the RTU/PLC. the HMI data base then reads the points and update the display.
is it correct??? please help.