AUTOMATION INTERVIEW QUESTION
50
QUESTION IN INTERVIEW FOR AUTOMATION ENGINEERS:
AUTOMATION INTERVIEW QUESTION
1.
What is Automation?
Combination
of :
Mechanical
system
Control
system
Information
Technology is called automation.
2.
What are the different components used in automation?
The
components of automation system include
RTD, Thermocouple, Pressure, Flow, Leve; etc)
Control
system which includes PLC, DCS & PID controllers
Output
devices / actuators like drives, control valves.
3.
What are the different control systems used in Automation?
PLC
based control system
DCS
based Control system
PC
Based automation system
4. Explain PLC?
PLC is an digital computer which is used for automation of electromechanical device such as control of machine.
plc consist multiple input output.
PLC is an digital computer which is used for automation of electromechanical device such as control of machine.
plc consist multiple input output.
5. Difference between RELAY & PLC ?
Relay is electromachanical switch but plc is programming controller.
PLC
works for analog I/Os such as PID loops etc. whereas a relay cannot.
6. Difference between PLC & DCS ?
DCS: In Dcs is multiple program in one pages.That is the controller sub system performs the
control functions, the history node connects the data, the IMS node gives
reports, the operator station gives a good HMI, the engineering station allows
engineering changes to be made.
PLC:
The system has processor & I/O’s and some functional units like basic
modules, communication modules and so on. Uses a SCADA for visualization.
Generally the SCADA does not use a central database.
7.
What is PC based control system ?
In
PC based control system, the CPU of computer acts as processor, the PCI based
cards are used for connecting Input and Output. The RAM acts as memory. Hard
disk is used as storage device. Currently this systems are very useful when the
large data is to be proceed with very high speed.
8.
What is Encoder ?
A
feedback device which converts mechanical motion into electronic signals.
9.
Which are the leading PLC providers ?
The
leading PLC providers include
Siemens (S7 200,S7 300,S7400)
Rockwell Automation : Allen Bradley (Micrologix, SLC, PLC, Control Logix)
Grouppe
Schneider : Modicon ( Nano, Micro, Premium, Quantum)
10.
What is DCS company name ?
The
leading DCS providers include
Yokogawa
: CS 3000 , CS 5000 (Earlier Centum Excel, Micro Excel)
Honeywell
: TDC 3000
ABB
- Freelance 2000
11.
What is SCADA software / MMI providers ?
The
leading SCADA software / MMI providers include
Wonderware
: InTouch
Intellution
iFix (Earlier FixDMACS)
Siemens
: WinCC
Allen
Bradley : RS View ( Earlier Control View)
Supervisory Control And Data Acquisition Software :
Wonderware InTouch:
12.
What is SCADA ?
SCADA
: Supervisory control and data acquisition
MMI
: Man Machine Interface
HMI
: Human machine Interface
This
acts as an operator station. The operator can monitor as well as control the
process parameters from this stations. Apart from online process data the
operator will have access to historical and real-time trends, alarms and
reports.
13.
What are Features of SCADA software ?
The
common features of SCADA include;
Dynamic process mimic,
Trends,
Alarm,
Connectivity with hardware,
Recipe management etc.
Dynamic process mimic,
Trends,
Alarm,
Connectivity with hardware,
Recipe management etc.
14.
Applications of SCADA.
SCADA
systems has many applications right from industrial automation,
power distribution to water management.
power distribution to water management.
15.
What is name of SCADA companies
Invensys
Wonderware InTouch
Siemens
WinCC (Earlier COROS)
Allen
Bradley RS View (Earlier Control View)
GE
Fanuc Simplicity
16.
Types of Wonderware SCADA packages
Development
+ Runtime + Network (DRN) / Runtime + Network (R+N) and View Node
D+R+N
: With this package development and editing of the
application is possible, Runtime monitoring and control of the plant is
possible and Networking is possible.
R+N
: With this package development and editing of the
application is NOT possible, Runtime monitoring and control of the plant is
possible and Networking is possible.
17.
What type of licensing patterns used in the SCADA software
Typically
two types of licenses are used in the SCADA
Dongle
Key : It is a hardware lock which can be put on the communication port of the
PC.
Software
Lock : Here the software code is the license. Typically you can put the code
while installation or transfer the code from Floppy to hard-disk.
18.
Various EXE files used in InTouch Software and there role
InTouch : It is an application
manager. Using this you can create new application. Move between various
applications.
View : Windowviewer. This will start Runtime application.
From this you can monitor and control the plant.
WM : WM.XE is Window maker. This will start the
development package in InTouch. Using this you can you can develop the
application.
19.
Types of Window ?
Replace : Automatically closes any window(s) it intersects
when it appears on the screen including popup other replace type windows.
Overlay : Appears on top of currently displayed window(s)
and can be larger than the window(s) it is overlaying. When an overlay window
is closed, any window(s) that were hidden behind it will reappear. Clicking on
any visible portion of a window behind an overlay window will bring that window
to the foreground as the active window.
20.
What is Symbol Factory ?
Symbol
Factory contains symbols which can be readily used in the application. The
symbols is contains include various Tanks, Reactor, Pipes, Icons, Flags.
21.
What type of user input used in InTouch ?
User
inputs include data entry Discrete, Analog, String/Message, Sliders and
pushbuttons.
22.
What type of animation can be given in InTouch ?
Colour
Fill
% Fill, Blinking
Size Control
Location
Orientation
Visibility
Action
Hide Show Window
% Fill, Blinking
Size Control
Location
Orientation
Visibility
Action
Hide Show Window
23.
What are trends ?
Graphical presentation of time versus quantity.
24.
What are Alarm and Events in InTouch?
Alarms
and Events are the notifications used to inform operators of process activity:
Alarms represent warnings of process conditions that could cause problems, and
require an operator response. A typical alarm is triggered when a process value
exceeds a user-defined limit. InTouch uses for types of alasm LOLO, LO, HI and
HIHI.
Events
represent normal system status messages, and do not require an operator
response. A typical event is triggered when a certain system condition takes
place, such as an operator logging into InTouch.
25.
Security management
Security
provides the ability to control whether or not specific operators are allowed
to perform specific functions within an application. Security is based on the
concept of the operator "logging on" to the application and entering
a "User Name" and "Password." (The application developer
sets up each operator with a "User Name," a pre-assigned
"Password" and an "Access Level" via the
Special/Security/Configure Users..command either in WindowMaker or WindowViewer.)
When
a new application is created, the default "User Name" is
"Administrator" with an access level of 9999 (which allows access to
all security commands).
26.
What is the use of Scripts in InTouch ?
Is
a way of writing logic in InTouch. InTouch has its own instructions and way of
writing program.
Application
: Linked to the entire application.
Window
: Linked to a specific window.
Key
: Linked to a specific key or key combination on the keyboard.
Condition
: Linked to a discrete tagname or expression.
Data
Change : Linked to a tagname and/or tagname.field only.
27.
What is driver ?
A
software which allows a computer to access the external devices using com ports
or communication cards.
28. What is DDE ?
Dynamic
Data Exchange is the facility developed by Microsoft for exchanging the data
between various programs.
DDE
has three important settings
Application
/ Server name , Topic Name and Item Name
29.
Communication with software (Excel)
DDE
settings for Excel
App.
Name - Excel,
Topic
Name – [book.xls]sheet1
Item
Name – Cell Address ie (R1C1)
DDE
settings for InTouch
App.
Name – View
Topic
Name – TAGNAME
Item
Name – Name of tag
30. What is cable name of plc?
.profibus
.M.p.i
.profibus
.M.p.i
31.
How to have two way communication between Excel and InTouch ?
Create
a I/O Tag Name with following detail
Application
name : Excel
Topic
Name : [XXXX.xls]sheet1 ie XXXX.xls is actual excel file used in application.
Sheet 1 is the spreadsheet where the data is kept.
Item
Name : R1C1 ie Actual Address of the Cell where the data is kept.
Programmable
Logic Controller - General
32.
What is PLC?
PLC
means Programmable Logic Controller. It is a class of industrially hardened
devices that provides hardware interface for input sensors and output control
element. The field I/p include element like limit switches, sensors, push
button and the final control elements like actuator, solenoid/control valves,
drives, hooters etc
33.
Applications of PLC
PLC
can be used in almost all industrial application solutions right from small
machine to large manufacturing plants. Even it caters applications of redundant
systems at critical process plants
33. Role of PLC in Automation ?
PLC
plays most important role in automation. All the monitoring as well as the
control actions are taken by PLCs. PLC Senses the input through I/P modules,
Processes the logic through CPU and memory and gives output through output
module.
34.
Role of CPU ?
This
component act as a brain of the system.
CPU
consist of Arithmetic Logic Unit, Program memory, Process image memory,
Internal timers and counters, flags
It
receives information from I/P device, makes decisions depending upon the
information and logic written and sends information through the O/P devices.
35.
Role of Power supply in PLC system ?
Power
supply provides system power requirement to processor, I/O and communication
modules. Typically the power supply has input voltage 120 V – 230 V AC or 24 V
DC and back plane output current 2 A to 5 A at 5 V DC
36.
Role of Rack or Chassis in PLC system ?
A
hardware assembly, which houses the processor, communication and I/O modules.
It does following functions.
Power
distribution
Containment
of I/O modules
Communication
path between I/O module and CPU
The
chassis are available in different slots in various PLC systems. Additional
chassis can be connected using chassis interconnecting cable.
37.
What is role of I/O modules ?
Electronic
plug in units used for interfacing the i/p and o/p device in the machine or
process to be controlled.
I/P
module receives data from i/p devices (Pushbutton, Switches, Transmitters) and
send it to processor. The O/P module receives data from processor and send it
to output device (Relay, Valves).
Digital/Discrete
:- Sends and Receives On/Off signal
Analog
:- Sends and receives variable input or output signals.
38. Role of EEPROM memory module?
This
module is inserted into processor system for maintaining a copy of project (PLC
program). This is helpful in case of memory corruption or Extended power loss.
39.
Communication module
Communication
modules are used either for communication between external hardware or software.
The hardware can be PLCs (same or other make), Controller, I/O module, smart
transmitters. The software can be SCADA software, MIS system or programming
software.
40.
Difference Between Fixed and Modular PLCs ?
In
non modular PLCs the processor will have inbuilt power supply and I/Os in one
unit.
The
modular PLC, will have separate slots for components like Power supply, I/O
modules. You can select the I/Os or power supply as per the need.
41.
What are the Types of I/Os ?
Ø Local
– These are the I/Os placed in the PLC main rack containing CPU. These I/Os are
connected to CPU through backplane.
Distributed
- These are the I/O placed at remote location from the main rack containing the
CPU. These I/O’s are to be connected on communication bus like control net,
device net or FIP I/O.
42.
What is meaning of resolution in I/O cards in PLCs ?
It
is the minimum change in i/p parameter which can sensed by the i/p card. As far
as Digital I/O is concerned it takes only one bit for operation. In case of analog
input the resolution determines how much bits are used for input or output. For
example a 12 bit resolution card means the input will come as 0 to 4095 count
(2^12). For 16 bit data the counts will be from 0 – 65536(2^16). More the
resolution the data will be more accurate
43.
What is an Analog Input Module ?
An
I/O module that contains circuits that convert analog input signals to digital
values that can be manipulated by the processor. The signals for pressure,
flow, level, temperature transmitters are connected to this module. Typically
the input signal is 4-20 mA, 0-10 V
44.
What is Analog Output Module ?
An
I/O module that contains circuits that output an analog dc signal proportional
to a digital value transferred to the module from the processor. By
implication, these analog outputs are usually direct (i.e., a data table value
directly controls the analog signal value).
45.
What is meaning of universal analog input card?
Normally
there are different cards for different signals. But in universal input card
the same channels can be configured for RTD, Thermocouple, Current or voltage
input.
46.
Give examples of I/P and Output connected to PLCs
Digital
I/P (Pushbutton, Switches )
Analog
I/P (Temp, Pressure, Flow, Level)
Digital
O/P (Solenoids valves, Contactors)
Analog
O/P (Control Valves, Speed)
47.
Explain Source and Sink Concept ?
Sinking
– When active the output allows the current to flow to a common ground.
Sourcing
– When active, current flows from a supply, through the output device and to
ground.
48.
What is forcing of I/O ?
Forcing
the I/Os means making the desired status of I/O in PLCs irrespective of its
status coming from the field.
49.
Scan cycle of PLC
PLC’s
scan cycle follows following path Scan cycle of PLC
Input
Image Updation
Process
Logic Execution
Output
Updation
50.
What is meaning of scan time in PLC?
Scan
time is the Time required to read the I/P, Process the logic and update the
output in one cycle.
0 comments: