HMI and MMI denotes devices, but SCADA refers only
software, which can loaded in any computer.
HMI and MMI are one and the same (H-Human and M-Man). Both
gives same meaning. It depends on supplier nomenclature.
But SCADA is an advanced version of this (Its like
difference between MS dos and Unix).
In SCADA, data history can be provided whereas it is
generally not possible to get in MMI or HMI.
HMI and MMI are cheaper and more suitable for small
applications compared to SCADA.
Hey, HMI and MMI are same, Graphical units. You can say,
Hardware Which can give view of system's process. One can
input data from it as well.
Now a days we can have PLC's which have graphical units but
usually process related decision making is not work of
GU,they are only done through if operator decides something.
In case of SCADA we can have all decision making and
Graphic display through it. Hence in that case you can
operate your plant through SCADA or can integrate number of
PLC and HMI in single SCADA to operate from main control
room as supervisory unit.
HMI & MMI both are same.
HMI is a harware device by whcih we can control the process
by changing status such as ON/OFF, cetpoint etc,
SCADA is a graphical representation of a system which
monitor,control & display data in a process,
For lage scale application we use SCADA & for small scale
application we use HMI.
HMI does not require any communication software while scada
MMI- Man Machine Interface
HMI- Human Machine Interface
Initailly MMI layer was name given to computers of Control
room to intrface (to view, to modify, to log data) with DCS
system. Later on even ladies started working in process and
control room so they change to Human Machine Interface. HMI
layer consists of many operator consoles and an engineering
SCADA is Supervisory Control amd Data Aquization.. This is
a vendor made program usually for PLC. Initially PLC was
made for dedicated package (AI, DI and DO ) but later on it
was started using for Contols, so it was required to
modify, log the data in the computer so each vendor develop
software compatible with PLC hardware which gives facility
for operator to watch, control and save history of the
HMI (Human Machine Interface) and MMI (Man Machine
Interface) are the same and have discussed earlier in
SCADA (Supervisory Control & Data Acusition) is a software
package which uses aur local control systems (eg. DCS or
PLC) to control or monitor " Our REMOTE location
If our Field (Hazerdouse area) and Control room (NON
Hazerdouse area) are is same geographical locations then we
dont have any need of SCADA.
But if our field and control room have different
geographical locations (Like main control room of
Offshores, gas plants / supply stations all over the
country etc) then we need SCADA integration with our MCR
When a timer is placed in RS Logix 5000 with preset value
less than its scan time it is malfunctioning. i.e., if the
preset is set to 30ms still the timer TT bit is counting
till 150ms(its scan time). Any solution for the problem?
Can we place a Control Panel in Hazardous area Group IIC ?
If 'yes' then is there any approval required?
If 'yes' then there is any specific IP rating or any
If 'Yes' What is MOC of control panel?