Hello, we are using Modicon Quantum 586 series PLC in Hot standby configuration, Problem is that PLC-A running as primary goes Offline and control shifts to PLC-B.When we reset the PLC-A it becomes standby. So we need to identify the possible causes for PLC-A going Offline because it is happening very frequently for the last 4-5 days and our plant is very crucial and we want to avoid any shutdown So please suggest any possible rectification during running plant conditions.