Changing the user program in RUN

Dear friends,

i was reading this article How can I get an overview of the S7-400 memory concept?  but one point i could not understand which is:

"Do you wish to be able to change the user program in RUN mode, and is the program too big for the internal RAM? If so, this would necessitate the use of a RAM memory card. When using a RAM memory card, the system must be battery-operated so as to back up the RAM memory card data and the data in the internal RAM if there is a power failure."

This means if i use FLASH memory card i will be not able to change the user program in RUN mode.

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Split from MEMORY CONCEPT DOUBT.

Dear vipz,

Thank you  for your reply.

But now i am in doubt because in some S7-300 CPUs there is no integrated load memory,and the load memory is an external FLASH memory but i can make any change and downloading it directly to the CPU without stop.i mean i can open any FB and change it and give download without stopping the CPU.

Dear vips,

Actually it is not clear.The problem is that  there is no document from Siemens that describes the concept or describes how the program will be copied from the load memory to the work memory,If i am able to know this process then i will able to know witch situations stop the CPU during the copying process.

From my experience, maybe this will help (I will explain using the newer S7-300 PLCs with MMC - Micro Memory Card).

In order to download in RUN, there must be enough available memory in the MMC (and CPU RAM) to accept your block(s) you wish to download.

Example, if your MMC has 128K, of which 120K is used, you have 8K available.  If your block(s) you wish to download at one time is more than 8K, you will not be able to download in RUN.  But, if you download one block at a time, and each one is less than 8K, you can download in RUN.  The size of your block can be obtained by viewing the block properties.

Dear sdyson,

Thank you very much.

But again we don't know the procedure of copying the program from the RAM to ROM. so i am not able to control the downloading process .Also when you give download by step 7 some actions will be taken by the step 7 such like downloading some blocks before another blocks.This action also is not well specified.

Hello,

look at this article, hope it shows you what you want:

https://support.industry.siemens.com/cs/document/15389520/what-is-the-effect-of-the-step-7-function-copy-ram-to-rom?dti=0&lc=en-WW