:: Home Page            
 Advertise your Business Here     
Browse  |   Placement Papers  |   Company  |   Code Snippets  |   Certifications  |   Visa Questions
Post Question  |   Post Answer  |   My Panel  |   Search  |   Articles  |   Topics  |   ERRORS new
   Refer this Site  Refer This Site to Your Friends  Site Map  Bookmark this Site  Set it as your HomePage  Contact Us     Login  |  Sign Up                      
Categories >> Engineering >> Instrumentation


 Civil Engineering interview questions  Civil Engineering Interview Questions (3119)
 Mechanical Engineering interview questions  Mechanical Engineering Interview Questions (3299)
 Electrical Engineering interview questions  Electrical Engineering Interview Questions (13431)
 Electronics Communications interview questions  Electronics Communications Interview Questions (2385)
 Chemical Engineering interview questions  Chemical Engineering Interview Questions (420)
 Aeronautical Engineering interview questions  Aeronautical Engineering Interview Questions (77)
 Bio Engineering interview questions  Bio Engineering Interview Questions (17)
 Metallurgy interview questions  Metallurgy Interview Questions (80)
 Industrial Engineering interview questions  Industrial Engineering Interview Questions (165)
 Instrumentation interview questions  Instrumentation Interview Questions (2394)
 Automobile Engineering interview questions  Automobile Engineering Interview Questions (107)
 Mechatronics Engineering interview questions  Mechatronics Engineering Interview Questions (38)
 Marine Engineering interview questions  Marine Engineering Interview Questions (45)
 Power Plant Engineering interview questions  Power Plant Engineering Interview Questions (79)
 Engineering AllOther interview questions  Engineering AllOther Interview Questions (1203)
What is the difference between HMI,SCADA and MMI,not
 Question Submitted By :: Instrumentation
I also faced this Question!!     Answer Posted By  
# 1
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.
Is This Answer Correct ?    49 Yes 18 No
Rajesh J
# 2
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.
Is This Answer Correct ?    27 Yes 4 No
# 3
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
requires it.
Is This Answer Correct ?    9 Yes 2 No
# 4
First about HMI and MMI:

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

About SCADA:

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
process parameters
Is This Answer Correct ?    7 Yes 0 No
Parag Pathak
# 5
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
control system.
Is This Answer Correct ?    8 Yes 2 No
Malik Shams-ul-arfeen
# 6
SCADA :- Its a software package which can be installed in
PC to create user defined program.

HMI :- Its an Electronic module with pre installed program
(which can be editable) and control buttons.

But SCADA and HMI doing the same functions.

SCADA & HMI(MMI) refers to a system that collects data from
various field devices to monitor and control the process
Is This Answer Correct ?    16 Yes 23 No
Ibrahim S
# 7
SCADA: It is a full of software package or visualized
software this we can develop a diagram
(eg:process level.tank level) as per your field instrument
located in your industry.

HMI: It is also give the same meaning but in hmi hardware
part also available. in HMI no need of communication
software but in SCADA it is must(eg:RS-LINX CLASSIC..etc)

MMI:HMI and MMI both are same,earlier this was called MMI
now we are calling HMI.
Is This Answer Correct ?    5 Yes 14 No
Manikandan - Panruti

Other Instrumentation Interview Questions
  Question Asked @ Answers
What is pressure,What is temperature,What is flow,What is level Petrofac 4
How to work DCS? how to get the signal from Field Instruemtns to PIB to Console? Invensys 2
what are different types of cables used in instrumention how to calibrate a level transmitter online ( rosemount )   1
In s7-200 we use HMI TD-200C , what that C stands for........ plz reply   2
different between calibration range and instrument range ?   2
How will you select suitable Instrument for Process line/Tank/Vessel?   4
My rtd working well at the same time r/i converter is not working properly.when power is given to is giving 30mA and getting 2.4 mA if i remove the compensate leads No matter how many ohms.why it is happening like so?what is the solution?rtd range-0-200deg c& 4-20 mA o/p.please give me solutiin anyone......   1
A temperature sensor (RTD) connected via a temperature transmitter is adjusted to give an output of 4ma at 60 deg and 20 ma at 600 deg. This output (4-20ma) from the transmitter is connected to an IGBT-inverter to control a high speed (-12,000 to +12,000 RPM) DC motor. And in the inverter it is programmed as, for 4ma the motor speed will be -3,000 RPM and for 20ma the motor speed will be +10,000 RPM. The question is : If the motor speed is +5,500 (RPM), what will be the temperature? (-sign indicates that the motion is in reverse direction).   8
who discoverd ohms law? HPCL 6
generally transmitter power supply having some range(12v to 35v) but the out put(4-20 mA) must same for given input.If we vary the power supply voltage then output mA also to be change according to V=IR. Is there any voltage regulator in the transmitter ?   1
Tell me the field calibration procedure step by step with diagram of temperature transmitter, temperature indicator, flow indicator, level indicator, control valve, thermocouple, pressure indicator (digital & analogue).   1
For more Instrumentation Interview Questions Click Here 

Copyright Policy  |  Terms of Service  |  Articles  |  Site Map  |  RSS Site Map  |  Contact Us
Copyright 2013  All Rights Reserved.   ::