HMI means Human Machine Interface a touch screen compact electronic equipment which controls industrial processes at a same time.
On HMI the user can view current data,log its data in .CSV file,control connected equipments connected with it.HMI used RS 485 Half wave / Full wave communication I . e 3 wire /5 wire communication .
RS485 Half Duplex /3 wire :-
In this the user cab only read data from the field, can’t control it as the data come one way from field only.
Rs485 Full Dulpex :-
In this the user can read as well as write data I.e User can view data from the field and also controls it due to 2 way communication I.e Full Duplex
HMI are generally used in production, manufacturing, Power Plant, Dairy Plant,Automation, Control Panels,Packaging Machines, HVAC system I.e Heat Ventilation & Air Conditioning system,Solar Power Plants,Chemical Mixing Plant,Printing Industry etc.