CompactLogix Memory consumption

Hello all,

I am doing a project with a CLX 1769-L32E. It has 192DI, 48DO, 8AI, 20AO.
The thing is that I barely built any logic and 168kb of memory is gone.
I add an integer in the controller tags and it takes 72 bytes (instead of 2?).
I add a tag of type pump (my UDT 8 bytes long) and it consumes 88 byte.
I have a FBD routine I add an input reference in a FB and it takes about 800bytes.

I notice that the application sucks the memory very fast.
In a similar project I was using an S7-300 with 192kb an no-one ever looked the memory consumption. Same for Modicon M340 and ABB's AC500.

Am I doing something wrong here?
The only things in the app at the moment are the Hardware configuration, the UDTs I made, a couple of AOIs and a routine in ST that takes the physical IO and maps them in tags. I am amazed that this takes 160kb of memory.
If the memory consumption is like that then I wont get even halfway in my app.

Regards

When you create a Tag in the controller, you're also creating an internal identifier and storing the Tag name and datatype information in the Tag Database.

When you configure I/O modules you're also creating many module-defined Tags and information about the module.

So creating Tags and defining I/O is actually pretty memory-intensive, compared to RLL or ST routines.

The good news is that if your application does exceed the memory capacity of the 1769-L32E, there are several CPUs you could substitute.

From what we are used to, a 780kb CPU is considered a big one. It is good to know how CLX consumes its memory as I thnik in this project we miscalculated that.

A few weeks ago, I had drafted up a little info on the memory usage of some of the instructions, etc., for the Logix controllers, while using a 1769-L32E for testing. This was for a reply to a thread regarding the number of instructions allowed on one rung in a Logix controller.

A figure of 2,000+ instructions on one rung was mentioned at one stage, while wondering how far further they could go. The simple answer is they could stay going until they run out of memory. I had posted this fact in an earlier reply, but had not highlighted it, and so I felt it was missed as the conversation continued about the possible limit.

For one reason, or another, I decided not to post it. I can't remember, but I may have saved the info for another time?

I'm at home now, but when I'm in work later I'll check see if I kept it. It explained in a little more detail what Ken has outlined. If I had just deleted it, oh well!

Regards,
George