The document presents an overview of discrete input modules in programmable logic controllers (PLCs), focusing on their role in interfacing with on/off field input devices such as switches and limits. It outlines the tasks performed by PLC input modules, including signal sensing, conversion, isolation, and communication with the processor. Additionally, it includes diagrams and simulations related to the operation of discrete input modules.

1. I N S T R U M E N T A T I O N & C O N T R O L
E N G I N E E R I N G D E P A R T M E N T
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SARDAR VALLABHBHAI
PATEL INSTITUTE OF
TECHNOLOGY
PATEL PARIXIT H.-140410117035
GUIDED BY :- DR. RAKESH B. PATEL

2. Topic:-Discrete Input module
block diagram and wiring
Programmable
Logic Controller
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3. I/O devices connected to PLC
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4. What is discrete input ??
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 The most common type of I/O interface module is
the discrete type.
 This type of interface connects field input devices of
the ON/OFF nature such as selector switches,
pushbutton, and limit switches.
 The classification of discrete input covers bit
oriented input.

5. Discrete input
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6. Input module perform
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 PLC input module perform four task.
1. Sense when a signal is received from a sensor on
the machine.
2. Convert the input signal to the correct voltage level
for the particular PLC.
3. Isolate the PLC from fluctuations in the input
signal’s voltage or current.
4. Send a signal to the processor which sensor
originated the signal.

7. discrete input module block diagram
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8. discrete input module simulation
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9. discrete input module simulation
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10. discrete input module simulation
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Input logic is
“high”

11. discrete input module simulation
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LED is ON

12. discrete input module simulation
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Voltage across
LED =1.869V
So, LED ON

13. Input module wiring connection
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14. THANK YOU
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