Interview Questions.

Question 1. What Is Plc?

Answer :

PLC approach Programmable Logic Controller. It is a class of industrially hardened devices that offers hardware interface for input sensors and output manage detail. The area I/p include detail like limit switches, sensors, push button and the very last manage factors like actuator, solenoid/manipulate valves, drives, hooters and so forth.

PLC Senses the input through I/P modules, Processes the common sense through CPU and memory and gives output thru output module.

Question 2. Applications Of Plc?

Answer :

PLC can be utilized in nearly all business utility answers right from small device to large production flora. Even it caters packages of redundant structures at important technique flowers.

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Question 3. Explain The Role Of Plc In Automation ?

Answer :

PLC plays most important function in automation. All the monitoring as well as the control actions are taken by way of PLCs. PLC Senses the input via I/P modules, Processes the good judgment thru CPU and memory and gives output via output module.

Question 4. Explain The Role Of Cpu ?

Answer :

This issue act as a mind of the system.

CPU include Arithmetic Logic Unit, Program memory, Process photo reminiscence, Internal timers and counters, flags It gets information from I/P device, makes decisions depending upon the records and common sense written and sends records thru the O/P gadgets.

The CPU’s are outstanding with following functions:

Memory capacity
Instruction set supported
conversation choice
time required to execute the control software.
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Question 5. Explain The Role Of Power Supply In Plc System ?

Answer :

Power deliver presents machine power requirement to processor, I/O and conversation modules.

Typically the strength supply has input voltage 120 V – 230 V AC or 24 V DC and again plane output cutting-edge 2 A to 5 A at five V DC

Instrumentational Engineering Interview Questions
Question 6. Explain The Role Of Rack Or Chassis In Plc System ?

Answer :

A hardware assembly, which houses the processor, verbal exchange and I/O modules.
It does following features.
Power distribution
Containment of I/O modules
Communication path between I/O module and CPU
The chassis are available in one of a kind slots in numerous PLC structures. Additional chassis may be linked using chassis interconnecting cable.
Question 7. What Is Role Of I/o Modules?

Answer :

Electronic plug in gadgets used for interfacing the i/p and o/p tool in the machine or method to be managed.

I/P module receives records from i/p gadgets (Pushbutton, Switches, Transmitters) and ship it to processor. The O/P module receives records from processor and ship it to output device (Relay, Valves).

Digital/Discrete :- Sends and Receives On/Off sign

Analog :- Sends and gets variable input or output alerts

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Question 8. Explain The Role Of Eeprom Memory Module?

Answer :

This module is inserted into processor system for retaining a duplicate of mission (PLC program). This is beneficial in case of memory corruption or Extended strength loss.

Question nine. Difference Between Fixed And Modular Plcs?

Answer :

In non modular PLCs the processor may have inbuilt power supply and I/Os in a single unit.
The modular PLC, can have separate slots for components like Power deliver, I/O modules. You can pick out the I/Os or energy supply as in step with the need.
Scada Interview Questions
Question 10. What Are The Types Of I/os?

Answer :

Local – These are the I/Os positioned within the PLC fundamental rack containing CPU. These I/Os are related to CPU thru backplane.

Distributed/Remote – These are the I/O positioned at far off area from the principle rack containing the CPU.

These I/O’s are to be linked on verbal exchange bus like control net, device internet or FIP I/O.

Question 11. What Is Meaning Of Resolution In I/o Cards In Plcs ?

Answer :

It is the minimal alternate in i/p parameter which could sensed by using the i/p card. As some distance as Digital I/O is worried it takes best one bit for operation. In case of analog input the resolution determines how lots bits are used for input or output. For example a 12 bit decision card way the enter will come as zero to 4095 rely (2^12). For 16 bit facts the counts could be from 0 – 65536(2^16). More the decision the facts might be more accurate

Siemens PLC Interview Questions
Question 12. What Is An Analog Input Module ?

Answer :

An I/O module that contains circuits that convert analog input signals to virtual values that may be manipulated through the processor. The signals for pressure, waft, degree, temperature transmitters are linked to this module. Typically the input signal is 4-20 mA, zero-10 V

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Question 13. What Is Analog Output Module ?

Answer :

An I/O module that includes circuits that output an analog dc signal proportional to a digital price transferred to the module from the processor. By implication, these analog outputs are typically direct (i.E., a information table fee without delay controls the analog signal price).

Question 14. What Is Meaning Of Universal Analog Input Card?

Answer :

Normally there are extraordinary cards for special alerts. But in frequent enter card the equal channels may be configured for RTD, Thermocouple, Current or voltage enter.

Question 15. Give Examples Of I/p And Output Connected To Plcs?

Answer :

Digital I/P (Pushbutton, Switches )
Analog I/P (Temp, Pressure, Flow, Level)
Digital O/P (Solenoids valves, Contactors)
Analog O/P (Control Valves, Speed)
Simics Interview Questions
Question sixteen. Explain Source And Sink Concept ?

Answer :

Sinking Source kind modules gives out the modern to the field virtual devices even as sink type modules draw present day while the tool is in excessive nation

Sinking – When lively the output permits the current to waft to a commonplace floor.

Sourcing – When lively, current flows from a supply, thru the output tool and to floor.

Question 17. What Is Forcing Of I/o ?

Answer :

Forcing the I/Os manner making the desired status of I/O in PLCs regardless of its popularity coming from the sphere.
In certain cases while there is trouble in receiving subject enter /output, we are able to force the i/Os in order that the logic takes desired state.
Industrial Automation Engineer Interview Questions
Question 18. What Is Meaning Of Scan Time In Plc?

Answer :

Scan time is the Time required to study the I/P, Process the logic and update the output in one cycle.

Instrumentational Engineering Interview Questions
Question 19. What Is Typical Scan Time In Plcs ? What Affects Scan Time ?

Answer :

Typically it's far much less than 10 ms. It depends on the complexity of logic, PID algorithm and so forth.

Question 20. How To Program Plcs ?

Answer :

Every PLC manufacturer have their personal software program for programming the PLC. For example Siemens makes use of Simantic S7 Manager, Allen Bradley uses RS Logix and Modicon makes use of PLC seasoned programming software program.

The programming language used is

Ladder Logic (LD),
Statement List (STL),
Functional Block Diagram (FBD),
Sequential Function Chart (SFC),
Instruction List (IL) and many others
Abbreviations Interview Questions
Question 21. What Is Ladder Diagram ?

Answer :

This is a programming language, which expresses a program as a series of “coils” and “contacts”, simulating the operation of electromechanical relays. The resultant application is the equal of an equation, that's achieved constantly in a combinatorial way. The gain of this language is the familiarity many electricians have with the simple operation of relays. Disadvantages include the complexity of large, cross-related packages, and the problem of expressing such non-binary features as motion control and analog I/O.

Question 22. What Is Redundancy ?

Answer :

The capability to switch from primary device to standby equipment mechanically without affecting the manner under control. Redundancy method provision for standby module. In case of failure of 1 module is running technique, the standby module takes over. Hot redundancy way the changeover of manage from active processor to standby processor in less than 1 test time.

Question 23. What Is The Need Of Redundancy?

Answer :

In essential methods, it's far critical to run the plant without failure. In such case it's far vital to have redundancy in order that despite the fact that one gadget fails the redundant gadget can take care without affecting plant.

Question 24. Explain The Types Of Redundancy?

Answer :

CPU redundancy: In case of CPU failure the standby CPU takes care of the plant

Power Supply redundancy: In case the energy supply fails the standby strength supply takes manage of the situation.

Communication : Multiple conversation channels are furnished to take care of verbal exchange failure

I/O Redundancy : Multiple I/O channels are furnished to attend to enter or output failure.

HMI Development Interview Questions
Question 25. What Are Components Of Redundant Plc System ?

Answer :

Typical factor on Schneider Redundant PLCs

The backplane used is either four slot o6 6 slot with

Power Supply
Controller with built-in Modbus Plus and Modbus ports
Optional dual cable Modbus Plus
Optional fiber optic Modbus Plus
CHS Hot Standby module
Dual cable Remote I/O Head
The master and Standby configuration ought to be equal

Supervisory Control And Data Acquisition Software : Wonderware InTouch

Question 26. What Is Scada ? Role Of Mmi/hmi Scada In Industrial Automation?

Answer :

SCADA : Supervisory manage and statistics acquisition

MMI : Man Machine Interface

HMI : Human system Interface

This acts as an operator station. The operator can reveal as well as manage the technique parameters from this stations. Apart from on-line process records the operator can have access to historic and actual-time trends, alarms and reviews. The operator can supply instructions to control hardware for beginning the valve, alternate the set point, begin the pump and so forth..

Question 27. What Are Features Of Scada Software ?

Answer :

The commonplace functions of SCADA encompass Dynamic system mimic, Trends, Alarm, Connectivity with hardware, Recipe control etc.

Scada Interview Questions
Question 28. Some Of The Leading Leading Scada Companies?

Answer :

Invensys Wonderware InTouch
Siemens WinCC (Earlier COROS)
Allen Bradley RS View (Earlier Control View)
Intellution iFix (Earlier Fix DMACS)
GE Fanuc Simplicity
Question 29. Types Of Wonderware Scada Packages?

Answer :

No. Of I/Os – Wondeware InTouch comes is 64, 128, 256, one thousand and sixty four,000 tags package.

Development + Runtime + Network (DRN) / Runtime + Network (R+N) and View Node

D+R+N : With this package development and editing of the utility is feasible, Runtime monitoring and control of the plant is feasible and Networking is feasible.

R+N : With this bundle improvement and enhancing of the utility is NOT possible, Runtime monitoring and control of the plant is possible and Networking is possible.

Factory Focus : With this package improvement and editing of the utility is NOT feasible, Runtime monitoring is feasible however manage of the plant is NOT viable and Networking is possible. This package is used a view node

Question 30. What Type Of Licensing Patterns Used In The Scada Software?

Answer :

Typically  types of licenses are used in the SCADA software

Dongle Key : It is a hardware lock which may be put on the verbal exchange port of the PC.

Software Lock : Here the software program code is the license. Typically you could placed the code at the same time as set up or switch the code from Floppy to difficult-disk.

Question 31. Various Exe Files Used In Intouch Software And There Role?

Answer :

InTouch : It is an application supervisor. Using this you can create new utility. Move among various programs.

View : Windowviewer. This will begin Runtime application. From this you could display and manage the plant.

WM : WM.XE is Window maker. This will start the improvement bundle in InTouch. Using this you could you could broaden the utility.

Question 32. Explain The Types Of Window ?

Answer :

Replace : Automatically closes any window(s) it intersects while it seems at the screen including popup different update kind windows.

Overlay : Appears on top of presently displayed window(s) and can be larger than the window(s) it's miles overlaying. When an overlay window is closed, any window(s) that were hidden at the back of it'll reappear. Clicking on any seen part of a window at the back of an overlay window will carry that window to the foreground as the lively window.

Popup : Similar to an overlay window except, it constantly stays on pinnacle of all other open windows (even supposing some other window is clicked). Popup home windows usually require a reaction from the consumer if you want to be eliminated.

Question 33. What Is Symbol Factory ?

Answer :

Symbol Factory consists of symbols which may be effortlessly used in the application. The symbols is carries consist of various Tanks, Reactor, Pipes, Icons, Flags.

Siemens PLC Interview Questions
Question 34. What Type Of User Input Used In Intouch ?

Answer :

User inputs consist of facts entry Discrete, Analog, String/Message, Sliders and pushbuttons.

Question 35. What Type Of Animation Can Be Given In Intouch ?

Answer :

Colour Fill, % Fill, Blinking, Size Control, Location, Orientation, Visibility, Action, Hide Show Window

Question 36. What Are Trends?

Answer :

Trends approach graphical illustration of statistics.
“Real-time” and “Historical. You can configure each fashion items to show graphical representations of a couple of tagnames through the years. Real-time tendencies permit you to chart as much as 4 pens (facts values), even as Historical traits can help you chart up to 8 pens.
Real-time traits are dynamic. They are up to date continuously during runtime with anything time span given in configuration. You can not scroll the real-time developments to look previous facts.
Historical traits provide you with a “photograph” of facts from a time and date inside the beyond. They aren't dynamic. Unlike real-time tendencies, historical developments are handiest updated while they're told to achieve this both thru the execution of a QuickScript or an motion by means of the operator, for instance, clicking a button. You can zoom in / zoom out the traits. You also can get right of entry to the previous information.
Simics Interview Questions
Question 37. What Are Alarm And Events In Intouch?

Answer :

Alarms and Events are the notifications used to tell operators of manner interest: Alarms represent warnings of system situations that might cause issues, and require an operator response. A normal alarm is brought on while a process fee exceeds a user-defined limit. InTouch uses for forms of alasm LOLO, LO, HI and HIHI.

Events represent normal device reputation messages, and do no longer require an operator reaction. A regular occasion is brought on while a positive machine situation takes vicinity, along with an operator logging into InTouch.

Question 38. Explain About Security Management?

Answer :

Security presents the ability to control whether or not unique operators are allowed to carry out particular features inside an application. Security is based totally on the idea of the operator “going online” to the application and getting into a “User Name” and “Password.” (The utility developer units up every operator with a “User Name,” a pre-assigned “Password” and an “Access Level” through the Special/Security/Configure Users..Command both in WindowMaker or WindowViewer.)

When a brand new application is created, the default “User Name” is “Administrator” with an get right of entry to degree of 9999 (which lets in get admission to to all protection instructions).

Question 39. What Is The Use Of Scripts In Intouch ?

Answer :

Is a manner of writing logic in InTouch. InTouch has its own instructions and way of writing software.

Application : Linked to the entire application. Window : Linked to a selected window.

Key : Linked to a selected key or key mixture on the keyboard. Condition : Linked to a discrete tagname or expression.

Data Change : Linked to a tagname and/or tagname.Subject simplest.

Question 40. What Is Driver ?

Answer :

A software which lets in a computer to access the external devices the use of com ports or communication playing cards.

Industrial Automation Engineer Interview Questions
Question forty one. What Is Dde ?

Answer :

Dynamic Data Exchange is the ability developed via Microsoft for exchanging the facts among various packages.

DDE has three crucial settings:

Application / Server call
Topic Name
Item Name
Question forty two. Explain The Communication With Software (excel)?

Answer :

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
Abbreviations Interview Questions
Question forty three. How To Monitor The Data From Intouch To Excel ? Ie One Way Communication From?

Answer :

InTouch to Excel.
In Excel worksheet write a formulaTAGNAME!A1
A1 is name of tag in InTouch
Question 44. How To Have Two Way Communication Between Excel And Intouch ?

Answer :

Create a I/O Tag Name with following element Application name : Excel Topic Name : [XXXX.Xls]sheet1 ie XXXX.Xls is actual excel document utilized in application. Sheet 1 is the spreadsheet wherein the information is stored. Item Name : R1C1 ie Actual Address of the Cell where the facts is kept.

Question forty five. What Is The Scan Cycle Of Plc?

Answer :

PLC’s test cycle follows following course Scan cycle of PLC

Input Image Updation
Process Logic Execution
Output Updation
Question forty six. Explain The Communication Module?

Answer :

Communication modules are used both for communique among outside hardware or software program. The hardware can be PLCs (same or other make), Controller, I/O module, smart transmitters. The software program may be SCADA software program, MIS machine or programming software program.