F5 LTM V.11.2.1: Synchro automatic at midight

Thanks for your answer, How to write this crontab to do the synchro every midnight? graphic or via command line?and how to activate it?

my device group name is: Device-Group Active LTM name: canal_ip5_4200LB.cdn Standby LTM name: canal_th2_4200LB.cdn