Motion control

Hi Everyone,

I'm trying to get a hydraulic ram to move in a IF ELSE kind of a way using true false statement and RSLogix 500 Pro.

RAM:
------x========|
z-----0-----y

currently I'm using a greater than and limits statement, such that if x[position of ram]<y[position desired] move towards y. I'm able to get it to move to y where my problem lies is that when I want it to go to a new position z the rung telling it to go to y engages promptly after x goes back over y. Any ideas on how to get the rung that contains the y command to stop until the ram has reached z?

Thank you

EDIT: The rate at which the RAM extends and retracts are different, going to y it is a PID style function while extending towards z is full open using a proportional solenoid.

Try a slightly different approach.

"If ram sees position z, it is now NOT going to position z, it IS going to position y"
"If ram sees position y, it is now NOT going to position y, it IS going to position z"

Ignore the current position, just latch each direction in until it gets to where it's going.

The only other thing you need is a "first start" situation catch, where it may not be at either y or z, has not decided to go one way or the other yet, and needs to pick a direction.

"If NOT going to y and NOT going to z and NOT already at y and NOT already at z, then go to [end of your choice]"

You sould not have a rung dedicated to going to a specific point but a rung that has the cylinder going to a specific target.

For instance

F8:1 holds the position for point y
F8:2 holds the position for point z

Your rung driving the motion should use a different register for instance F8:0.

When you want to go to y, move F8:1 to F8:0
When you want to go to z, move F8:2 to F8:0

In your logic you are always going to F8:0 but the code changes the number in F8:0 so that you will go do different positions.

Hope this makes sense....

There is probably a lot of other things to consider but this is the basis of going to different points.

Thank you for your help, I'll be testing these ideas today. Will post an update