Dynamic RPI Setting

JankyPLC

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Does anyone know if you can SSV an Ethernet module RPI timer from a CompactLogix Processor?

I have a machine with a 1734-ENBT card that, according to the Task Monitor, is running at 98% capacity. Connected to it, one WinCC Runtime, 10 1734-AENT racks, and 4 Powerflex 525s.

This machine has VHSC cards in the remote IO racks which are tied to encoders on motors for positioning feedback. The machine runs in stages and during one stage I'm trying to achieve very precise movement. Right now its proving to be fairly inconsistent. My hope was to be able to turn down the RPI timers on the Point IO racks and the VFDs during this time to gain precision.

It needs to be dynamic because I have to turn the others up to compensate to prevent the card from faulting out. Does anyone know if this is possible, or if there's a better way around this that doesn't require a second ENBT card to be purchased?
 
welcome to the forum ...

TIP: if you're dealing with "high speed" operation on a CompactLogix system (not ControlLogix) then you need to be aware that the CompactLogix platform makes use of a "Dedicated I/O Task" which has a Priority of SIX ...

basic idea: in some "high speed" cases, you might need to take the CompactLogix out - and replace it with a ControlLogix instead ... (ControlLogix doesn't use the I/O Task arrangement) ...

DISCLAIMER: the last time I investigated this "I/O Task" setup - I was using a CompactLogix with a Revision of 16 ... I'm not sure whether or not later versions have the same arrangement - but I know for a fact that the V16 system I was experimenting with had SERIOUS ISSUES when it came down to using high speed I/O signals ...

good luck with your project ...
 
My first thought is what do you mean by "very precise movement"?

If it's so precise that you are thinking of changing your comms rate, it might be time to look at better hardware than PF 525 drives.
 
Rob, I currently have my logic in a cyclical task at 5.0ms, priority of 5 to stay above the IO task. I’m on version 20 for what it’s worth. I know compactlogix (-768-L45) probably isn’t the best controller for this nor 525 in this configuration but it’s an addition to an existing machine and the equipment is already installed. I’m just tasked with making it work as best it can.

Basically I’m looking to achieve <1/16” repeatable tolerance with motors with encoders built in (1024ppr) running through 50:1 gear boxes to 3” diameter friction drive rollers.

What makes me feel like the RPI has something to do with it is the fact that I can maintain 1/8” tolerance on the same machine with motors on starters tied to 50:1 reduction gearboxes with the encoders on the output shaft of the gearbox with both encoder and starter going through point IO.. If that works, shouldn’t this with VFDs give better precision considering I can slownthe drives down upon final positioning?

To be honest I feel like I’m missing something that would help me immensely, but maybe it’s just the limitation of the equipment. Regardless, do either of you know if you can SSV RPI? Or what the difference is between card RPI and Point IO rack RPI? Unfortunately googling RPI comes up with a wealth of raspberry pi info and not much Rockwell.
 
Rob, I currently have my logic in a cyclical task at 5.0ms, priority of 5 to stay above the IO task. I’m on version 20 for what it’s worth. I know compactlogix (-768-L45) probably isn’t the best controller for this nor 525 in this configuration but it’s an addition to an existing machine and the equipment is already installed. I’m just tasked with making it work as best it can.

Basically I’m looking to achieve <1/16” repeatable tolerance with motors with encoders built in (1024ppr) running through 50:1 gear boxes to 3” diameter friction drive rollers.

What makes me feel like the RPI has something to do with it is the fact that I can maintain 1/8” tolerance on the same machine with motors on starters tied to 50:1 reduction gearboxes with the encoders on the output shaft of the gearbox with both encoder and starter going through point IO.. If that works, shouldn’t this with VFDs give better precision considering I can slownthe drives down upon final positioning?

To be honest I feel like I’m missing something that would help me immensely, but maybe it’s just the limitation of the equipment. Regardless, do either of you know if you can SSV RPI? Or what the difference is between card RPI and Point IO rack RPI? Unfortunately googling RPI comes up with a wealth of raspberry pi info and not much Rockwell.

I looked it up on Knowledgebase and this is what I found

Check you acceleration and deceleration rates on the drive. I didn't look up the parameter numbers.

If the drive is not reacting to your speed changes quickly, you may be over-shooting

SSV RPI.JPG
 
I looked it up on Knowledgebase and this is what I found

Check you acceleration and deceleration rates on the drive. I didn't look up the parameter numbers.

If the drive is not reacting to your speed changes quickly, you may be over-shooting

Just a heads up, I think Rockwell has asked that we don't post content directly from areas of the KB that require support contracts. It's fine to paraphrase and communicate the information though.
 
Thanks for the help everyone. I believe my deceleration is set to .1 second and I’m commanding the speed down from 45hz to 10hz as I approach my stopping point before sending my stop signal. I’ll dounle check the rate and see what stop parameter I’m using. If I’m remembering mysettings correctly all of these things have incrementally helped, just trying to figure out any others that may help even more.

For some reason I didn’t see that on the KB. We do have a support contract so I have access. I guess I should search harder next time. :geek:
 
Just a heads up, I think Rockwell has asked that we don't post content directly from areas of the KB that require support contracts. It's fine to paraphrase and communicate the information though.

Sorry - missed the TechConnect level on the Access Level :(
 
Does anyone know if you can SSV an Ethernet module RPI timer from a CompactLogix Processor?

I have a machine with a 1734-ENBT card that, according to the Task Monitor, is running at 98% capacity. Connected to it, one WinCC Runtime, 10 1734-AENT racks, and 4 Powerflex 525s.

This machine has VHSC cards in the remote IO racks which are tied to encoders on motors for positioning feedback. The machine runs in stages and during one stage I'm trying to achieve very precise movement. Right now its proving to be fairly inconsistent. My hope was to be able to turn down the RPI timers on the Point IO racks and the VFDs during this time to gain precision.

It needs to be dynamic because I have to turn the others up to compensate to prevent the card from faulting out. Does anyone know if this is possible, or if there's a better way around this that doesn't require a second ENBT card to be purchased?

Where is the task monitor for the ENBT? I only see a task monitor for the processor ... nothing that shows 'Task Monitor' in RSLinx either.

I'm interested since I've been told that the life-span of Controlnet is limited and I will need to move to ethernet eventually. Right now I don't use ethernet for anything IO related ... except communication to the DeltaV ... and that's the only method that has enough bandwidth ...
 

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