1746-HSRV camming

We have a customer site that has standardized on SLC's and wants this upgrade to be done on a SLC (they already have RSLogix500, training, spares, etc.). We are fully aware this would be simpler in the ControlLogix realm, but it is what it is.

We want to index a wire along a spools axis based on the rotational position of the spool (encoder off spooler via 1746-HSCE) and the wire diameter (move one wire width per spooler revolution over the course of the revolution).

Our plan was to cam the controlled axis (indexer servo via 1746-HSRV) off of a feedback axis (spooler encoder via 1746-HSCE).

Is the correct way to go about this? Also, in the 1746-HSCE manual it mentions camming is possible via incremental moves, but I cannot find any examples. Has anyone seen an example of this? Thanks.

correction

Also, in the 1746-HSCE manual...

Typo. It is in the 1746-HSRV manual.

I don't have any particular experience with the HSRV but since no one else jumped in I thought I would.

I don't think you will be able to do what you want to do with the parts listed. The camming they talk about is poor man's camming. The HSRV will execute linear blended moves. This means it will string two moves together at the point that the acceleration of the first move is expected to end. So if you queue up enough moves of the appropriate distance you can get what looks like a faceted cam move.

What you want is more of a coordinated move. I don't think the HSRV will accept any external axis information. So you really can't coordinate the HSRV to anything.

You may be better off trying to see if a 1746-QS can be made to work in this situation. You may have to switch to some different feedback but I'm pretty sure the -QS can slave a controlled axis to a real master, which is what you are trying to do. Better yet you may be able to slave both axes to a virtual master.

There are others who haunt the forum that will be able to tell you if this is feasable.

Keith

Thanks Keith.

It looks like the 1746-QS is out of our budget.

I think the poor man's camming will be sufficient. We'll set the traverse axis (1746-HSRV) up to do discrete incremental moves based on the rotational position feedback of the spooler (via 1746-HSCE).

If you're interested, I'll post a commented .pdf of the code here of what ended up working well.

I'm pretty sure i understand what you were doing. Buit, as they say, a picture is worth 1000 words. If you can, post a PDF of what you did.

Keith

The job got delayed, but now we are done.

It ended up working very well.

The HSRV manual implied (or at least I deduced inaccurately) that the motion commands were 'one-shotted', ie give a move command and you must complete or cancel that move command before another command can be given.

It turns out that the HSRV looks at the move command dynamically (at least every PLC scan) and adjusts. We just looked at the rotational position of the spooler via the HSCE module, did some math, added some lead position, and updated the motion command on the fly.

It all just worked smoothly.

John
I am looking at doing a similar Thing Can you post up your PDF
so I could have a look at it
Cheers Matt

The RMC75 will do what you want easily. The RMC75 has camming built in.
http://www.deltamotion.com/products/motion/rmc70/
If you have a SLC5/05 you can talk to a RMC75E easily over ethernet. The RMC75 actually shows up on RSLinx as a SLC5/05. The other option is to use a serial port or even stand alone. The RMC75 is much more powerful than a SLC5/0?

Here is the SLC code. It worked, but that environment is a little clunky; I would have preferred a platform that supported motion better.

Since the platform we used doesn't support true camming, we ended up setting the position reference of the spooler off of the angular position of the spool, with a lead factor based on the current speed.

This ended up making a very nice wrap-up on the spool. I wouldn't recommend this solution for high-speed robotics or the like; our movement to be 'cammed' was relatively slow and predictable.

Good luck.