Stopping Drum from Running at Power Up

[Scott59]

How do I keep the Drum from running at PLC power up? I am using a V 700 with 18-E3-XB module. When i power up the unit, it automatically runs the Drum sequencer without any start buttons being pushed. I have tried linking the direct contact in front of the drum scanner to the start button, Tried indirect contacts. Coils or every kind. changing the MB settings, even removed the contact from the ladder and left the scan FB hanging in the ladder without any connection, when i did that it still started all by its self but only ran the First line of the drum...Ahhhh... Im new to the ladder logic/programming stuff, But this is hard to understand.The help files indicate that if the drum scanner is inactive...the sequencer is inactive..but the sequencer starts all by itself. What am i doing wrong?

[AlexUT]

Hi

Use first Drum step with 00:00:00.00 time.

Then start is from second step.

BR.

[Scott59]

Thanks AlexUT... that works...I linked the Start button to the Next Step function..now how do i make the next step only advance one step? when i touch the Start button(link to next step) it will advance 2,3,or more steps before I get my finger off the button. 

[cantcliff]

You're running into a common problem using input buttons.  The program is scanning several times during the time you have the button pressed. You need to prevent your code from executing your start rung more than one time.

 

There are a lot of ways to do this.

 

I tend towards Positive transition contacts because most my programs are relatively small but those aren't always preferred as they can cause weird issues when you start using a lot of them.  I have yet to have issues.

 

You can also work multiple rungs together to control the logic so that a single press one registers for a single scan.