Drive multiple speed with different reference using PLC

Drive nultiple speed with different reference using PLC

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Automatic Lamp Control

Automatic Lamp ON/OFF Control in a Godown using PLC

Problem Statement

In traditional setups, when someone enters the godown (storage area), they manually press a switch that turns all lamps ON simultaneously. This leads to unnecessary energy consumption, especially when only certain segments are in use.

A solution is needed to optimize power usage with segment-wise automation.

Diagram:-

Automated Solution Using PLC

We’ve implemented a simple automation system using a PLC (Siemens S7-1200) and the TIA Portal software.

The godown is divided into three segments, each with:

• One lamp
• One switch
• Interlocking logic to prevent multiple lights from running at once

Operation Logic:

• When the user presses Switch 1 (SW1) → Lamp 1 turns ON.
• The system locks control of Lamps 2 & 3 until Lamp 1 is turned OFF.
• This pattern is repeated for each segment, enforcing sequential access to lighting and conserving energy.

PLC I/O List

Digital Inputs	Digital Outputs
SW1 = I0.0	Lamp 1 = Q0.0
SW2 = I0.2	Lamp 2 = Q0.1
SW3 = I0.3	Lamp 3 = Q0.2

 

Ladder Logic Summary

• Network 1:

• Lamp 1 (Q0.0) is triggered via NO contact of SW1 (I0.0)
• NC contacts of other switches are used to ensure interlocking

• Network 2:

• Lamp 2 (Q0.1) uses NO contact of SW2 (I0.2)
• Interlocked via NCs from other segments

• Network 3:

• Lamp 3 (Q0.2) uses NO contact of SW3 (I0.3)
• Follows similar interlocking structure

Runtime Test Scenarios

Input Conditions	Output States	Lamp Status
I0.0 = 1	Q0.0 = 1	Lamp 1 ON (Lamp 2 & 3 OFF)
I0.2 = 1	Q0.1 = 1	Lamp 2 ON (Lamp 1 & 3 OFF)
I0.3 = 1	Q0.2 = 1	Lamp 3 ON (Lamp 1 & 2 OFF)

 

Explain Not equal (< >) instruction using example

Application:-Explain not Equal instruction in the PLC. Write PLC program for explanation using ladder diagram language in the Programmable Logic Controller (PLC).

Components:-Programmable logic controller, HMI panel, wires, 24 VDC lamp, 24 VDC power source.

Diagram:-

Explanation:-

Consider a simple example for explanation of not equal instruction in the PLC. Here we have taken simple HMI (Human Machine Interface) for display and programmable Logic Controller (PLC) for programming. Take two values, set value 1 and set value 2 for example. Here if both the value in the set value 1 and set value 2 equal then lamp will be OFF. So we need to use not equal (< >) instruction for above example.

Enter 20 value in the value 1 box and enter 20 value in the value 2 box so lamp should be OFF and if someone enter 21 value in the set value 1 box, lamp should be ON.

 PLC program:-

Write the ladder program for above application using ladder diagram language. Here for ladder logic we can use any supported PLC system like S7-1200, S7-300, S7-1500 or any other PLC which can support this instruction. For PLC logic we need digital inputs and outputs.

For our application lamp is digital output. Two set values from the HMI are input words.

Digital Output:-

Lamp=Q0.0

M Memory:-

Value 1:-MW10

Value 2:-MW12

PLC program Explanation:-

In network 1 two values are compared in the comparison instruction. Value 1 (MW10) is compared with Value 2 (MW12).Hence if both values are not equal, lamp (Q0.0) will be ON.

In not equal (< >) instruction, two operands are compared, we can set data type in comparator instruction.