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PLC Configuration

This document discusses PLC multiple outputs configuration and sequence logic. It provides examples of ladder logic diagrams with two outputs connected to a single contact, and with two inputs and two outputs, to start two pumps in parallel or satisfy start permissions. The document also describes how a sequence of outputs can be produced through the sequential closing of contacts in the ladder logic.

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290 views3 pages

PLC Configuration

This document discusses PLC multiple outputs configuration and sequence logic. It provides examples of ladder logic diagrams with two outputs connected to a single contact, and with two inputs and two outputs, to start two pumps in parallel or satisfy start permissions. The document also describes how a sequence of outputs can be produced through the sequential closing of contacts in the ladder logic.

Uploaded by

Instrumentation Tools
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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Instrumentation Tools

Learn Instrumentation and Control Engineering. Inst Tools covers topics of Industrial
Instrumentation, PLC, DCS, SCADA, Field Instruments, Analyzers and so on.
https://instrumentationtools.com

Author: Instrumentation Tools

Categories: PLC Tutorials

PLC Multiple Outputs Configuration

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PLC Ladder Rung with Two Outputs :


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With ladder diagrams, there can be more than one output connected to a contact. Figure 1.20
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shows a ladder program with two output coils. When the input contacts close, both the coils give
outputs.
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Also Read: PLC Latching Output Configuration

Example: In Some cases it is required to start two pumps in parallel by pressing a single start
button then the above logic may be useful.

InstrumentationTools.com
Instrumentation Tools
Learn Instrumentation and Control Engineering. Inst Tools covers topics of Industrial
Instrumentation, PLC, DCS, SCADA, Field Instruments, Analyzers and so on.
https://instrumentationtools.com

PLC Ladder Rung with two inputs & two outputs :

For the ladder rung shown in Figure 1.21, output A occurs when input A occurs. Output B only
occurs when both input A and input B occur.

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Example: Say we have a Single Start button to Start two pumps in parallel. But we have extra
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Start Permissive for Pump B only and it must be started on satisfying the permissive only. Note
that there is no permissive for Pump A in the above example. So Pump A will start on Pressing
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Start Button and Pump B will start on Satisfying the Start Permissive & with Start button
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pressing.
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PLC Sequence of Outputs or Sequence Logic

Such an arrangement enables a sequence of outputs to be produced, the sequence being in the
sequence with which contacts are closed. Figure 1.22 illustrates this with the same ladder
program in Mitsubishi and Siemens notations. Outputs A, B and C are switched

InstrumentationTools.com
Instrumentation Tools
Learn Instrumentation and Control Engineering. Inst Tools covers topics of Industrial
Instrumentation, PLC, DCS, SCADA, Field Instruments, Analyzers and so on.
https://instrumentationtools.com

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on as the contacts in the sequence given by the contacts A, B and C are being closed. Until
input A is closed, none of the other outputs can be switched on. When input A is closed, output
A is switched on. Then, when input B is closed, output B is switched on. Finally, when input C is
closed, output C is switched on.

Example: The above logic will be useful in sequence logic’s. For example for conveyor belt
action, Bag house logic, Sequence of on/off valves operation etc.

Also Read: PLC Logic Functions

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