PLC

List types of Controllers?

• PID
• Microcontroller: a computer implemented on a single chip, can be programmed, not expensive but sensitive to noise, and can't be used in industrial apps.
• PLC
• DCS
• SCADA

What are DCS, and DCS components?

Distributed systems connected by network for communications and monitoring.

DCS Componets 

1. Feild Control System
2. Enginerring Station: for I/O configuration
3. Opertor station: for monitoring 

What are SCADA, and SCADA components?

Highly distributed system used to control geographically scattered assets over thousands of square kilometers. Used to collect data and send alarms.

SCADA component:

1. Human Machine Interface (HMI) : for monitoring 
2. Supervisory (computer) system: gathers process data and sends commands to the process.
3. Remote Terminal Units (RTUs) : converting sensor signals, sending to the supervisory system
4. Programmable Logic Controller (PLCs) 
5. Communication infrastructure:  provides connectivity  

What is meant by PLC?

A Programmable Logic Controller (PLC) is a digital computer used for control; it replaced traditional relays due to their flexibility and reliability. 

Draw plc architecture and discuss the function of its components?

Central Processing Unit (CPU):

• The "brain" of the PLC.
• Executes the user program and controls the overall operation.
• Processes input signals and generates output signals.
• Manages system memory and communication with other devices.

Input Modules:

• Receive signals from sensors, switches, and other input devices.   
• Convert physical signals (e.g., voltage, current) into digital signals.   
• Transmit the digital signals to the CPU for processing.

Output Modules:

• Receive signals from the CPU.
• Convert digital signals into physical signals (e.g., voltage, current).
• Drive actuators, motors, solenoids, and other output devices.   

Power Supply:

• Provides the necessary power to the PLC and its components.   
• Ensures stable operation even in harsh industrial environments.  

Memory:

• Stores the user program, system data, and configuration settings.   
• Types of memory:
  • Program memory: Stores the user-defined program logic.   
  • Data memory: Stores temporary and permanent data.
  • System memory: Stores system configuration and diagnostic information.

Communication Interfaces:

• Enable communication with other PLCs, computers, and network devices.
• Common interfaces:
  • Serial ports (RS-232, RS-485)   
  • Ethernet
  • Fieldbus (PROFIBUS, CANopen)

Discuss PLC types?

• Fixed Input/Output: Low cost, does not support extensions.
• Modular: can expand by including new unit (extension)
• Rack: expensive; supports 256 input and 256 output.

Draw the Siemens PLC rack; illustrate the main components and their functions?

Slot 1: Power Supply

Slot 2: CPU

Slot 3: Interface Module: for rack-to-rack communication

In Any Slots: 

• Signal Modules: For input/output modules (Digital Input, Digital Output, Analog Input, and analog output)
• Function Modules (FM): (High speed counter, Temperature control,...)
• Communication Processor (CP): for the networking communication

List the category of choosing the industrial PLC?

1. Memory Size
2. CPU Speed/Speed of execution
3. Network capabilities 
4. Max no. of input
5. Max no. of output
6. Type of input (Digital/Analog)
7. Type of output(Digital/Analog)
8. Cost
9. Manufacture 
10. Vendor 

List the category of choosing the industrial sensors?

1. Accuracy
2. Resolution
3. Repeatability
4. Range
5. Linearity
6. Response Time
7. Cost
8. Environment

What is PLC programming Languages?

Concurrent

1. Ladder Logic (LD)
2. Function Block Diagram (FBD)
3. Structured Text (ST)
4. Instruction List (IL)

Squential

1. Squential Function Chart
2. Flow Charts

Compare PLC to PC?

PLC	PC
Programmable Logic Control	Personal Computer
Optimized for single task	Optimized for multitasks
Used in industrial environment for Control tasks	Used for personal tasks
Can operate in High temperature	Can’t operate in High temperature

Compare PLC to a microcontroller?

How to Start/Stop DC Motor, AC 1 Phase, AC 3 Phase Motors?

• DC, One Phase AC motors need relays to start/stop.
• AC 3 Phase motor needs condactor.

How to Change Direction for DC Motor, AC 1 Phase, and AC 3 Phase Motors?

• For a DC motor, just change positive and negative to change the motor direction.
• For AC 3 Phase: just change the power source between two phases
• For AC 1 Phase: Make the capacitor in series or in parallel with main coil to change the direction.

How to Change Speed for DC Motor, AC 1 Phase, and AC 3 Phase Motors?

• For a DC motor: increase volt and give power as pulses to avoid increasing Ampear (using pulse width modulation)
• For AC 1/3 Phase: increase AC frquancy. 

List Timers Types?

• S-On Delay Timer (S-ODT): Dealy output with TV value
• S-Off Delay Timer (S-OffDT): Output start directly with input and continues after input with TV value
• S-Pulse Extent Timer (S-PEXE): when get input signal a pluse with TV widths will out

Notes:

• S: Input Signal
• TV: Time Value ==> S5t#10s
• Q: Output Signl

List Counters Types?

1. S-CU: Counter up with no limits, need comparetor to catch the required value.
2. S-CD: Counter Down From PV to Zero, needs two SET, One when start and Second when Done.
3. S-CUD: Counter Up/Down, CU increase CV, CD descrease CV.

Notes:

• Q: Give outputs when CV>0
• CV: Counter Value ==> C#50
• S: Set CV with PV value
• R: Reset all to zeros
• PV: Preset Value

List Comparators Types (CMP)?

• Integer: One Word
• Double: Two Words
• Float: Two Words

CMP Operations

• >
• >=
• <
• <=
• =
• !=

Explain Analog to Digital Converer Module?

Siemens FC105 used to convert linear analog signal, to give digital output, it needs:

Inputs:

- En: Enable input

- Max input signal, 

- Min input signal, 

- Input signal: PIWx (Preferal Input Word, x refers to any address like 0,1,..)

- BiPolar: if 1 then it accepts positive and negative values; Zero means unipolar.

Outputs

- ENO: Enable output

- Err: Gives 1, or 8 incase of error

- Out: MDx (Memory Double x) 

Notes: I refer to input bit and PIW refer to Input Word (32 bit)

Example

- When Level Low, Open pump till high level, then start heater till 800c

- Open Q01 valve to extract the output with temperature 100c - 300 c

- Q02 gives output with temperature 400c-525c

- Q03 gives output with temperature 550c-700c