Memory Allocation in Control Logix

Ashwin

Member
Join Date
Mar 2003
Location
Columbia, MO
Posts
62
I had a few queries on the AB control Logix

1. Is there any possible means as to find out, how much of controller memory is left in the control logix PLC?

Ken probably you could answer this one, is AB moving in that direction where by users could know how much of processor memory is available.

2. Seems logical I cant, but can I delete, unused controller tags that get defined when i add I/O cards

3.When I add the D/A convertor to the system, I get an option of controller, input and output tags. On the A/D card, there is only the controller and the Input option..Why is it different on the D/A?

4. Is there any correlation between how much memory your Application file takes up on the desktop compared to what it would be in the processor of the PLC. Like right now my application file shows like 1.5MB on the desktop and we have like a close to 512 MB+the 64 MB that comes with the processor. and I know I am almost hitting the limit.

Could anyone reflect on these please!

Thanks
 
1. Currently, you have to download to the controller to find out how much memory is used. If the controller doesn't have enough memory, it won't download. They say V13 will show memory usage off-line.

2 & 3 - not sure what you're getting at

4. The .ACD file contains all tag descriptions and rung comments which are not downloaded to the controller. Also, the program is compiled before dowload (should get smaller?). If you use structured text, all of your source code and comments are downloaded.
 
2. I have never been able to. I don't think it's possible.

3. Having inputs from an output module is about the only way to get status information back from the module. The group you are calling 'controller' values are acutally configuration values. The outputs are the desired per-channel output data, as you would expect. The inputs contain module status, channel status and output readback values. The module status stuff is simply added to the input data coming back from the input modules so you don't notice it as a separate category.

Keith
 
At present there is no easy way to determine memory allocation except for the simple total used once you are online.

V13 will provide a tool for determining all memory allocation both online and ofline. Bear in mind there are two seperate memory blocks in CLX, one for the logic CPU and the other for the backplane CPU and at present there hasn't been any method for getting any visibility on usage.

Fortunately it usually didn't matter as you could always buy more RAM.
The good news is that V14 may see "Task Manager Tool" that will show full online performance and all resource usage.
 
I/O

Gerry! i beg to differ

This is what i noticed on my CLX. The system would go through its downloading tags and all that before it would give me a pop up with the error that Main program out of controller memory.

Well! in 2 and 3 i was refering to the fact that once i add the Analog Input and output cards..I see two types of Alias , the A/D channel has

Slot Number:I and Slot: C indicative of inputs and Controller tags

ON the D/A i notice, Slot: I, Slot: C, Slot:O. On the D/A i use only data on the Slot:O.data, so i was wondering why do we have slot:I.data there, when it was not to be used in the first place on D/A.


Keith is that what you were trying to explain. I was just not sure.

Ya! i called up AB and they said Ver 13 is going to be out in march.


sounds trival but how does one check controller memory online?

On second thoughts, how do i correlate that information to the number of tags i can create or the number of rungs i can add to the existing program.
 
Ashwin-

ON the D/A i notice, Slot: I, Slot: C, Slot:O. On the D/A i use only data on the Slot:O.data, so i was wondering why do we have slot:I.data there, when it was not to be used in the first place on D/A.

Keith is that what you were trying to explain. I was just not sure

Yes, that's what I was referring to. If you look at all the stuff in your analog input (A/D) structure that is above the actual data, it will match up loosely with the stuff in the analog output (D/A) input structure. In both cases this is fault and status information and can be useful. That structure is provided for you as an easy way to get this information from the analog output.

Keith
 
Gerry! i beg to differ

This is what i noticed on my CLX. The system would go through its downloading tags and all that before it would give me a pop up with the error that Main program out of controller memory.
OK - I made a long story short.
Slot Number:I and Slot: C indicative of inputs and Controller tags
Drop the "ler". These are Control (or Configuration - take your pick) tags for the module. You'll see these for all modules and they reflect what's in the configuration dialogue that pops up when you add a module.

As Keith explained, the input data from an output module (digital or analogue) is status info.
 
Thanks

Thanks guys.

On a different note, you guys from down under..do u follow the cricket there ? Whats the status of the kiwi team? Are the touring?
 

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