PLC Programming for Stepper Motor

Hello friends..

I’m posting new PLC project ‘PLC Programming for Stepper Motor’. This project includes the  techniques used, programming and interfacing. Advantages of PLC is that we can connect a Stepper motor Without any Driver Circuit (depends on Output rating of PLC).

Technique Used: (For Understanding Purpose Only)

·         Lets consider 4 line Stepper Motor(A,B,C,D and COM)

·         Also consider  4 step Truth Table

Truth table is shown below:

Above Truth table is just for reference. As per your requirement you can take your own table.

When considering PLC, no direct element is present to generate above sequence. Therefore many line programs are required.  Here I will explain how to write any type of stepper motor program by a simple method.

Here I am using timer function TON (Timer ON Delay). TON takes Delay to Turn ON, but we have to mention that Delay time.

Taking  4 TON Timer, these timer having different delay

(TON1 : TON2 : TON3 : TON4 :::: 1 : 2 : 3 : 4 )

The delay waveform shown below

TON4 is used for to reset all 3 TON timers. It will reset every time.

As per Above Waveform and Table we get 4 time period that is t1, t2, t3, t4. We have to write a program so that in every time period ‘t’ the program is made to run one STEP. So in 4 time periods 4 steps will occur. This will keep repeating.

Then for above condition we have to write logical expressions as shown below

Programming: 

As Per Above algorithm we write the program here. Control inputs are ON and OFF. Output lines are named as A, B, C and D.  Physical Switch for ON is NO Push button (Normally Open) and For OFF it is NC Push button (Normally Closed).

We are using Timer TON (Timer ON Delay) which takes a Delay time to turn ON.  We have to set that Delay time.

Because of continual switching of TON step sequences are generated.

Ladder Diagram:

In above program I have set delay for TON1, TON2, TON3 and TON4 as 1, 2, 3 and 4 seconds respectively.

For simulation purpose we can use Siemen’s LOGO SOFT (Click To Download) and the  ladder diagram generated using this software is shown below

Block Diagram:

Before connecting Motor:

      1)      Check the Ratings for PLC output Relay voltage and current.

      2)      If output Relay rating is less than motor voltage Rating then you have to use External Relay, it should be Actuated by a DC supply

Above precaution should be taken before making the connection, otherwise wrong ratings or connections will cause permanent damage to PLC.

All the best…

Please leave your queries in the comments section..

Thank you

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About Praveen S

Hello everyone, I am Praveen S, currently employed as "Technical Design Engineer" for Polycab Wires Pvt Ltd , I am a BE Graduate in EEE from NMAMIT Nitte (Karnataka, India). I am very passionate about learning and sharing my knowledge relating to the areas of "Electrical and Electronics". Here's my blog to share my ideas and to improve myself.