In my project I have 2 smart objects I have created 18 instances of one type of smart object and another 18 for second smart object all variables communicating through MODBUS so in my project I have two drivers for two smart objects I created total 36 instances from these two smart objects so I need to communicate 36 PLC ,I Configured IP for each plc in smart object driver 

I want to know how modbus driver request data from each PLC one by one PLC OR all PLC at same time?

because In service engine data update taking 1 to 1.5 minutes