AOI referencing Controller Tag for run mode reference

Sparkyman1 · May 19, 2017

Hey! Im working on a system with about 40 conveyors.

Now this system was originally designed to be controlled by switches on a control panel, and was later setup with a PanelView, then a control mode switch was added to switch between having the system in local control(switches) OFF and panelview control.

I want to make an AOI for the conveyers. And I would like to be able to reference what control mode the system is in as part of the AOI without creating an AOI variable that need to be referenced in the ladder logic.

Is there a way to do this? Basically an AOI with an unchangeable reference to a controller scope tag, I.E. checking an E-stop before allowing a conveyer to start?

labeledas · May 19, 2017

if you are asking if you can reference a controller or program scoped tag from your AOI without creating a variable, I think you will have to bite the bullet on this one I remember having issues with this 8 years ago and it seems it hasn't changed.

taken from page 21:

http://literature.rockwellautomation.com/idc/groups/literature/documents/pm/1756-pm010_-en-p.pdf

"There is no direct programmatic access to controller or program scope tags."

Sparkyman1 · May 19, 2017

I've read something about v18 adding support for alaising tags for AOi's but I can't seem to find a way to do it.

ELake20 · May 20, 2017

Nope.

It's a real bummer and something I hope they fix soon.

If you were programming in Siemens this is totally supported but in Rockwell world no dice (atleast I haven't been able to do it someone may chime in?)

My work around is configuring a UDT with my controller scoped variables I want to bring in to the AOI instead of each individual item so the link up process is easier.

Create a subroutine where you do your moves from controller scoped tags to the UDT. It's an added step but will give you the functionality you are looking for.

Sparkyman1 · May 20, 2017

Yeah I've pretty much already done that. I feel like the ability to alias a UDT or AIO is almost nessicary for their use to make sense my application.

Wouldn't it be nice to have 100 AOI's for OL faults and have them all reference back to the fault reset button without doing it on every single rung? It's crazy that they can't do that.

GaryS · May 20, 2017

You can do exactly what you want
Just create the AOI for the Overload
Create a In / Out parameter for the reset
as well as an output for faulted ( to trigger an alarm in the HMI)
Then when you add the AOI to your program in addition to the overload input tag reference the reset input to a global reset tag
The global reset can be an input or a tag set from the HMI or anything you want.
Every AOI can use the common tag as an input to reset, start, stop or whatever you want

Sparkyman1 · Jun 21, 2017

GaryS said:
You can do exactly what you want
Just create the AOI for the Overload
Create a In / Out parameter for the reset
as well as an output for faulted ( to trigger an alarm in the HMI)
Then when you add the AOI to your program in addition to the overload input tag reference the reset input to a global reset tag
The global reset can be an input or a tag set from the HMI or anything you want.
Every AOI can use the common tag as an input to reset, start, stop or whatever you want

Sorry I know this post is old, but are you saying that I just make a fault reset but as a input to the AOI everywhere that I use it on a rung? That's what I'm trying to avoid.

Reason being that I need to reference a system mode switch on all 40 AOI's, a fault reset bit on a 40 AOI's and it would also be nice to do things like latch on a global bit if ANY of the conveyors are forced on or faulted.

It would just be nice to have a rung with an AOI that only has one tag in, it the UDT for the conveyer, and not a bunch of golbal variables as inputs and outputs.

Sparkyman1 · Jun 21, 2017

ELake20 said:
Nope.

It's a real bummer and something I hope they fix soon.

If you were programming in Siemens this is totally supported but in Rockwell world no dice (atleast I haven't been able to do it someone may chime in?)

My work around is configuring a UDT with my controller scoped variables I want to bring in to the AOI instead of each individual item so the link up process is easier.

Create a subroutine where you do your moves from controller scoped tags to the UDT. It's an added step but will give you the functionality you are looking for.

I understand what your saying, I may end up doing it this way

labeledas · Jun 21, 2017

If what I am understanding is correct you want to reference a tag outside the AOI scope then no you can't do that, maybe there is a way but I have tried, it has to be passed into your AOI as an input or in/out. it sucks but I think they were aiming for complete encapsulation, still would have been nice to be able to reference other scopes

is there a reason you don't want to do this, the logic would be the same the only difference is you have to an extra input to your AOI and assign it

Sparkyman1 · Jun 21, 2017

labeledas said:
If what I am understanding is correct you want to reference a tag outside the AOI scope then no you can't do that, maybe there is a way but I have tried, it has to be passed into your AOI as an input or in/out. it sucks but I think they were aiming for complete encapsulation, still would have been nice to be able to reference other scopes

is there a reason you don't want to do this, the logic would be the same the only difference is you have to an extra input to your AOI and assign it

The AMOUNT of extra inputs and outputs is what I don't like. And making a quick change turns into making a change on every single rung.

I guess I can just assemble all of the system variables into a UDT and have one in/out UDT with the motor parameters and one in/out UDT for system variables

labeledas · Jun 21, 2017

I agree it sucks, I

for a few days trying to figure out a work around, but alas it's hand RA dealt I would like to think they had a reason, but at least it's better than what we had before or at least I think it is?

Paullys50 · Jun 21, 2017

Find and replace??

If you add a new input parameter, it will insert a '?' as the placeholder. If the required place holder is a global tag called 'E_Stop'...

dmargineau · Jun 21, 2017

labeledas said:
...I would like to think they had a reason...

The reason probably is the platform universal/global characteristics of the AOIs similar to any other pre-defined Logix instructions.

AOIs could be inserted within any Logix application no matter the hardware content/configuration thus defining said AOIs using hardware generated or controller scoped tags contravenes the intended functionality.

Or at least that's the way I see it...

Sparkyman1 · Jun 21, 2017

labeledas said:
I agree it sucks, I for a few days trying to figure out a work around, but alas it's hand RA dealt I would like to think they had a reason, but at least it's better than what we had before or at least I think it is?

Yeah, I really wish I could just grab a global variable right from inside the AOI, reason being that I'm adding functionality to this program as a learn, and i think I have went and changed one little thing on every single rung at least 5 times as I learn the "right" way to do something.

It isn't too bad to just grab a system variable UDT tag though, at least this way if I decided that I would like to access another system variable, I don't have to go back to every single rung and copy paste it in... I'll just add another member to the UDT!

The more time I spend working on this project, the more I learn. If I had to write this PLC and FTview program again it would only take a week or so... haha.

labeledas · Jun 21, 2017

dmargineau said:
The reason probably is the platform universal/global characteristics of the AOIs similar to any other pre-defined Logix instructions.

AOIs could be inserted within any Logix application no matter the hardware content/configuration thus defining said AOIs using hardware generated or controller scoped tags contravenes the intended functionality.

Or at least that's the way I see it...

I get that but it would have been nice to access objects outside it's scope via a modifier global. or parent. that would keep the intended functionality while allowing a bit more flexibility.

But now that I think about I see what your are saying it's probably because they wanted it to be a simple drag and drop fill in parameters and go, and not worry about creating outside dependencies which the AOIs has no means of tracking if they exist or not and could create confusion using poorly documented AOIs.

AOI referencing Controller Tag for run mode reference

Sparkyman1

Member

labeledas

Member

Sparkyman1

Member

ELake20

Lifetime Supporting Member

Sparkyman1

Member

GaryS

Member

Sparkyman1

Member

Sparkyman1

Member

labeledas

Member

Sparkyman1

Member

labeledas

Member

Paullys50

Lifetime Supporting Member

dmargineau

Lifetime Supporting Member

Sparkyman1

Member

labeledas

Member

Similar Topics