Kinetix, superimposing movements.

[Elcan]

Hi all,
I am not too experienced with some of the Allen Bradley motion instructions, and I'm translating a program from a Trio PLC to an Allen Bradley PLC.
The Trio instruction I need to translate is ADDAX. Please see attached picture.

What would be the RSLogix equivalent?

Thank you!

[kamenges]

Unfortunately I don't have anything in front of me to test this with right now. However, you should be able to issue two separate move commands to the same axis. The motion planner will combine the requirements of the two profiles to produce a combined move profile. Just use a different motion instruction for each move (different instruction tags).

Keith

[Elcan]

Originally Posted by kamenges

Unfortunately I don't have anything in front of me to test this with right now. However, you should be able to issue two separate move commands to the same axis. The motion planner will combine the requirements of the two profiles to produce a combined move profile. Just use a different motion instruction for each move (different instruction tags).

Keith

Isn't the second instruction buffered till the first one is finished?

[kamenges]

I don't believe so. It may depend on whether the moves are absolute or incremental. But I think the second move initiate and add to the second as long as none of the axis maximums are violated.

Keith

[ASF]

Again speaking only from memory - but check out the "Merge" feature of various motion instructions. I've never used it in anger, but from what I remember it allows you to determine whether a new motion command replaces already running motion commands, or is merged with them/added to them in some capacity. It might achieve what you're after

[kamenges]

It isn't as straightforward as I was making it out to be but it can be done.

I found a plc lying around here and set up a couple of virtual axes. If you do what I was originally saying you will simply update the motion parameters of the move in progress and end up with a move distance equal to the sum of the two moves, assuming they are both incremental. If one of them is absolute I suspect it is the absolute position offset by the incremental position. It all happens as a single move with the latest accel and max speed in force based on the last MAM to operate.

To do what you want to do (as far as I know) you need to use an additional virtual axis to provide the base move. You then need to gear the real axis to that virtual axis. In doing this you will have the real axis follow any move made by the virtual axis. Program an MAM for the virtual axis with the parameters of the "base" move. Program a second MAM for the real axis with the parameters of the "adder" move. In reality it doesn't matter which axis makes the base moves and which axis makes the adder moves. they are superimposed in either case.

This will result in something that looks like the attached.

Keith