Automation and Robotics 20ME51I_Week 5 Practicals.pdf

PLC, SCADA & HMI: INDUSTRIAL AUTOMATION
PRACTICAL HAND BOOK Page 102

19. Parts are moved on the conveyor. Count the number of parts collected at the end
of the conveyor and display it.
Problem Solution
a. Proximity switch is mounted to detect the parts.
b. Use output of proximity to counter as an input to increment data.
c. Most widely Inductive and Capacitive Proximity switches are used to detect parts.
d. Inductive Proximity are used to detect metal objects while to detect other objects,
Capacitive Proximity Switch is most widely used.
e. Mount this sensor according to the size of parts present on the conveyor and width of
conveyor so that this sensor can detect parts easily.
PLC Program
List of Inputs and Outputs
X0 = Start (Input)
X1 = Stop (Input)
X2 = Proximity (Part detection) (Input)
Y0 =Conveyor motor (Output)
C0 = Counter (Counter)

Program Description
a. Network 1&2 is the Start/stop rung used to start/stop the conveyor and counting
process.
b. Network 3 is to count the number parts collected. Counter with address C0 is to count
the number of parts collected. Whenever a part is detected by Proximity Switch, X2
goes true momentarily and it increments the value in the counter.
c. Network 4 is used to reset the counter using Counter bit C0.
Runtime Test Cases
Inputs Outputs Elements
X0= 1, X1= 0, Y0= 1 Conveyor Motor ON
X2 = 1 (Momentarily) Counter Incremented Counter
C0= 1, Counter Reset Counter

20. A feeder drops material on the conveyor which sends material for further process
through one more conveyor. Conveyor must start automatically when material is
dropped on it.
Problem solution:
a. Feeder has a motor mounted to feed material on conveyor belts.
b. Load cells are installed at the bottom of conveyor belts to detect if material is present on
the conveyor belt.
c. When material falls on conveyor belt 1, motor 1 should start, and when material in present
on conveyor belt 2, motor 2 remain On.
d. Switches can also be used sometimes to detect material’s presence. But for more reliable
operation, Load cells can be used as shown in the diagram above
PLC Program
X0, X1 = Start, Stop (Input)
X2 = Load cell of conveyor 1 (Input)
X3 = Load cell of conveyor 2 (Input)
M0 = Master Coil (Memory)
Y0 = Motor 3 (feeder) (Output)
Y1 = Motor 1 (Conveyor 1) (Output)
Y2 = Motor 2 (Conveyor 2) (Output)

Program Description
1. Network 1 is for Master Start/Stop the process.
2. Network 2 is to operate feeder motor 3 with output address Y0 which is operated when
Start PB is pressed and M0 coil enabled.
3. Network 3 is to operate Motor 1 of Conveyor 1 which is operated when Load cell 1
(X2) detects the presence of material.
4. Network 4 is to operate Motor 2 (Y2) of Conveyor 2 which is operated whenever Motor
1 is ON or as long as material is presence on the conveyor 2 which is detected by Load
cell 2 (X3).
Runtime Test Cases
Inputs Outputs Physical Elements
X0 = 1, X1= 0 M0 , Y0= 1 Start Motor 3
X0 = 1, X2 = 1 Y1 = 1 Start Motor 1
X0 = 1, X2 = 1 or X3 = 1 Y2 = 1 Start Motor 2

21. Parts are moving on the conveyor from one process line to other with a constant
speed. Out of 10-part, one part is taken out for quality check
Problem solution:
a. To detect the parts, detector such as proximity switch, optical sensors or any other
sensor is used.
b. Connect output of this detector to Input Module of PLC.
c. Give this detection, as an input the 16-bit counter (C0) which is incremented with
each part’s detection.
d. Set counter preset value to 10.
e. Operate Solenoid for a few seconds until the part is diverted for quality check.
PLC Program
X0, X1 = Start, Stop (Input)
X2 = Detector input (Input)
Y0 = Conveyor Motors (Output)
Y1 = Solenoid to operate gate (Output)
C0 = Counter to count 10 parts (Counter)
T0 = Timer to operate solenoid (Timer)

Program Description
a. Network 1&2 is Start and Stop the conveyor and subsequent process.
b. Network 3 comprises Counter which counts the number of parts detected by the detector
which is connected to X2, whenever a part is detected, X2 goes high momentary and
incrementing accumulator value of C0 Counter.
c. Network 4: When 10 parts are counted, counter bit C0 is used to operate Solenoid Coil.
d. Network 5: Assume that it takes 5secs to divert the part for quality check, 5secs of Timer
T0 is used which is driven by counter bit C0.
e. Network 6: T0 timer bit resets the counter Preset value to 0 which in turn unlatches
solenoid coil Y1 taking gate to its original position.
Runtime Test Cases
Inputs Outputs Physical Elements
X0 = 1, X1= 0 M0, Y0 = 1 Run Conveyor Motor
X2 = 1 (Momentarily) Accumulator = +1 Increment Counter
C0= 10 Y1 = 1, T0= 0 Energize Solenoid
T0 = 1 C0= 0 Reset Counter, De-energize Solenoid

22. After filling process, bottles are moved on the conveyor belt for packing process.
Detect if any empty bottle is left on the conveyor and remove it from the conveyor.
Problem solution:
1. Proximity sensors are used to detect bottles.
2. One proximity is calibrated such that it detects all the bottles passing on the
conveyor.
3. Other proximity is used such that it detects only empty bottle.
4. Use a Pneumatic Cylinder or blower to throw an empty bottle out of the conveyor
PLC Program
X0 = Start (Input)
X1 = Stop (Input)
X2 = Bottle Detector (Input)
X3 = Empty bottle Detector (Input)
Y0 = Conveyor motor (Output)
Y1 = Blower (Output)

Program Description
1. Network 1 When the system is started X0 is ON, conveyor motor coil Y0 with address
is energized.
2. Network 2&3 are used to operate bit shift register.
3. Network 4 is to operate Blower with address Y1.
4. Whenever conveyor motor is in RUN mode, empty bottles detected by the proximity
sensor with input X3 (Control bit), it sets Inter relay bit and is shifted left every time a
bottle is detected by bottle proximity with address X2.
5. From proximity to blower, distance is 4 steps. Hence bit M4 relay in the register is used
to operate blower and empty bottle is removed.
Runtime Test Cases
Inputs Output Physical Elements
X0 = 1 (Start PB) Y0 = 1 Run conveyor motor
X3 = 1, X2= 1 M0 = 1 Set first bit of bit register
X2 = 1 BSL = 1 Shift bit to left
M4 = 1 Y1 = 1 Activate blower

Automation and Robotics 20ME51I_Week 5 Practicals.pdf

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