Memory Size

If you have an existing project at least as large as the new project, make a copy, update the I/O, and then make copies of existing logic proportional to the amount of new I/O.

Let's say you have 1 OB, 10 FCs, 10 FBs, and 5 DBs (+ 10 instance DBs) in the original project.

Let's say your I/O count went from 100 to 150.

In OB1, copy half the networks, and paste to the bottom of OB1.

Select the 10 FCs and copy, then paste them.  They will duplicate the FC #.  Ignore that.

Select the 10 FBs and copy/paste.  Same for all the DBs.  Now in the system resources section of the project tree, there might be some DBs.  If there are quite a few, you might need to estimate the amount of system resource and add 50%.

If you then renumber all the blocks so they are unique and compile the project, portal will tell you how much memory you used.  I personally try to stay below 60% load memory usage...  It depends on the types of projects though.

Then you need to estimate the required scan time.  If you need faster scan time, you need more s7-1200's to share the processing load, connected as smart remote I/O (i-Devices) -- or s7-1500..

RJAF10

Hello! I have a question regarding the size of a program code. How can you determine or estimate the size of a program in order to select the correct PLC.

Best regards