SIMATIC S7-1200, CPU - 30kbyte

Hello everyone


I just want to start with learning PLC programming, so I need advice. I have SIMATIC S7-1200, CPU with integrated memory 30kbyte and it's not expandable. I want to programming some basic staff, like few coils, timers, pushbuttons, and connect it with HMI where also will be some graphs, pushbuttons, etc...my question is: Is this 30kbyte enough for that? How much I can do with 30kbyte?


Thank you,
Regards

I would expect you could write programs of well over 100 rungs with 30kbytes or memory. Of course it depends on how much memory is allocated for data, but certainly the kinds of tasks you mention are well within that PLC's capacity.

Through some very poor use of programming I did actually manage to fill the memory on a 1211 CPU. To do this, it took around 1000 data tags, roughly 300 rungs of logic, webserver and this was using a KTP400 basic HMI. Having refined that program it's now running at less than 20% memory capacity to do the same thing.
I also have another 1211 on a test bench that's set up to be able to play around with a pair of G120 drives and another KTP400 on a small profinet network.

Basically, memory isn't an issue at all for basic applications, but it's important to know that the 1211 cannot use IO modules.

For what the OP described, 30k memory ought to be plenty. Remember, the PLC manufacturer sized the memory to be sufficient for the typical application the PLC was designed to handle.

It should be plenty, I have an FX3U with 16kb of memory, the program is quite large, lots of memory addresses used for recipes, I have with some slick programming reduced the size but for your purpose should be plenty, each ladder component & functions take up some memory for example perhaps a a normally open contact in a ladder probably only takes a byte or maybe a word in it's compiled code, some maths functions may take a few bytes of memory so I would expect 30kb to give you probably a few hundred rungs.

This might be of interest to you, I have a program in an FX3U with 16k of memory, 10k is taken up with a file register I use for recipe handling (I suppose you could call it the equivelent of the S7 Data blocks perhaps 10 or 20 of them).
There are 427 ladders in 15 program/function blocks some are a little memory intensive as they are floating point calculations & data manipulation & there is still memory availlable.