Problem in programming arduino with gsm 800l

I can controller my 4 relay with my arduino and gsm800l , but I don’t know how can I program it to ^^ work for period for example for what I want : send message "ON RELAY1 30m " to gsm to arduino for make relay on just for 30min or any time i want … plz help me friends :frowning: :frowning:

Your problem is not clear bro. Are you trying to control 4 relays with an arduino using the SIM800L GSM module? or what are you trying to achieve?