PLC Program for Automatic Parameter Initialization when Power UP

Parameter Initialization when Power UP

This is PLC Program for Automatic Parameter initialization when power up.

Problem Description

• In many applications it is necessary to initialize some data when machine is powered up.
• Sometimes due to power failure, value in some parameters becomes zero.
• Due to this problem operator has to feed all data again or every time during power failure.
• When machine will get power up, at that time necessary parameters should be initialized automatically.
• Here we discuss this issue with some basic ladder logic.

Problem Diagram

Problem Solution

• In this case we need to write logic in PLC program so all parameters will be initialized automatically.
• We can also set manual initialization button so operator can initialize data during machine operation is running.
• Here we will consider machine set speed as a data and it will be initialized automatically when machine will turn on.
• If operator wants to reinitialize set speed during running cycle then he needs do it through initialization button.

PLC Ladder diagram

Here is PLC program Automatic Parameter initialization when power up.

List of PLC inputs/outputs

Inputs List

• Parameter Initialization Button : I0.0
• MW10 : Set Speed form Display

Outputs List

• Mw12 : Speed for drive

Program Description

• For this application we use S7-1200 PLC and TIA portal software for programming.
• This logic is used for parameter initialization.
• For first scan, we used here S7-1200 facilities of system Memory. Every PLC have its own system memory.
• Always ON bit, always OFF bit, first scan bit, and diagnostic status changed are the system memory for S7-1200 PLC.
• We can configure any memory address “M” for system memory. Here we configured M1.0 for first scan bit which is used for parameter initialization.
• We write for parameter initialization in Network 1. Here we use NO contact of First scan bit (M1.0) for moving initial 5 RPM in MW12(Speed for drive).By using MOVE instruction 5 RPM will be moved in MW12 . Add NO contact of Parameter Initialization Button (I0.0) for moving Initial 5RPM in MW12 (Speed for drive) manually.
• For editing data manually in running cycle we write logic in Network 2. Here operator can enter data in MW10 (SET SPEED) from the display and it will go in MW12(Speed for drive).
• For Example, Say we need to enter 100 RPM speed from display it will be written in word MW10 (Set Speed from display) and as per logic it will be moved in MW12 (Speed for drive), so motor will run on 100 RPM.

Runtime Test Cases

Note : The above PLC Logic provided for basic idea about application of PLC Program for Automatic Parameter Initialization when Power UP. The Logic is limited and not complete application.

Author : Bhavesh

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