LURBY

Powerflex Step Logic Positioning

3 posts in this topic

I have an application using a Powerflex 525 for positioning.  I really should be using a servo but the equipment is already in place.

I have it set up with three steps.  First step is my feed.  Jump to the second step (rapid return) with a Logic Input 1 command.  Jump to the third step (ends cycle) with a Logic Input 2 command.  I have "Positioning Mode" (parameter 558) set up in StpLogis-Lst so that if I stop at any point in the cycle I can restart where I left off. 

Everything works as it should.  It steps through the sequencer just fine.  The only problem that I am having is that if I stop it midway through a step it will not allow me to jump to the next step because the first step has not reached it's position.  For instance:  First step is an absolute feed motion in the forward direction for 5".  The second step returns this motion back to the home position.  If during the first step I stop it at 2" I can restart it and it will continue the last 3" no problem because it is an absolute move.  What if instead I wanted to go back home?  How do I jump to the next step if I have not completed the first step?

Share this post


Link to post
Share on other sites

You've set parameter 558 to Step Logic Last, which means the drive will, "Use Step Logic commands from last Step Logic step at last drive stop". In other words, the drive must complete a step and stop before it can continue to the next step. Have you tried using one of your digital input functions (parameters 62 through 66) as a Home command? Option 35 will make the input a home signal. The input must be on when the drive receives a start command, but I don't know if this will interrupt and over-ride a partially completed step logic command.

To jump from one step to another step out of sequence (or (presumably) before a step is complete) you would have to change parameter 558 to "3" Preset StepL, where it uses digital inputs to step it through a sequence. 

Have you considered putting an inexpensive controller in the system and just letting ladder logic monitor the steps and control the drive?

Share this post


Link to post
Share on other sites

I solved it.  I found the preset inputs.  Selecting them will jump to whichever step you want.

1 person likes this

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now