Gents,

I was far from Siemens PLC for a while and need to restore my knowledge.

Memory card in Step7-300 , if i down load program for first time , it’d go to work memory and if i lost power, would i loose the program or not?

If yes, should i copy Ram to Rom so i get permanent program with regardless of power situation?

And do we need at any time to reset PLC  through program or Simatic manager and down load it again for any reason or not? 
!

S7-300 or 400 which have Ram with battery ? When it came for first time especially S7-400 with default IP address. When i downloaded the program and battery is okay and i reset the program ? Do i need to download the program through Lan network?

When can i miss IP address and load whole program through MPI or through lan via default IP address ? Is it when power loss and faulty battery?

Thank in advance 

Hello;

You are asking for a lot of information on many different probkllems.

Let's start by giving you details on the memory concepts for the S7-300 and the S7-400 CPUs:

• How can you obtain an overview of the memory concept of SIMATIC S7-300 CPUs and C7 devices?

https://support.industry.siemens.com/cs/ca/en/view/7302326

Most S7-300 CPUs (except for the very first and oldest models) only use the MMC as load memory card, which is described in section 4 of the pdf inserted in the link.

• How can I get an overview of the S7-400 memory concept?

https://support.industry.siemens.com/cs/ca/en/view/7302549

Note that the S7-400 can have a RAM + batteries concept.and an EEPROM memory card (this is the one you need the Copy RAM to ROM function when downloading).

We can discuss IP addressing later, when you have confirmed your mempories on the s7-300 and s7-400 systems.

Hope this helps,

Daniel Chartier

Thanks Daniel for useful reply

But got to clarify

If i use memory reset while i’ve ram card ( external one)  program will be lost and got to download again via PG? 
If i use memory reset while i’ve flash card ( external one) , will do i need to down load again via Pg especially if internal Ram is part  of main program ? And how i know if Flash card has full program to start up or not?

. When do i need to use copy Ram to Rom? As per topic when you transfer program from PG to Cpu, it’s automatically copied to Ram or flash card?

.when overall reset can delete Ip addresses and send Cpu to default IP?

Thanks in advance 

Hello:

We are talking of S7-400 CPIs now, since a "recent" S7-300 using a MMC (EEPROM) card retains the dowloaded program in all circumstances.

First, I should point out that the IP address you set on the CPU or a CP 443-1 is part of the hardware configuration of your program. If the program is retained, the IP address is also retained. If you lose the contents of your memory card, the IP address is also lost.

If your S7-400 uses a RAM card, a download of the the program will load it to the memory card, which is supported by the battery pack. As long as the batteries are functional, the program in the RAM card is supported and the program cannot be lost. If the LEDs indicating battery fault light up and you do not put in replacements, when you power down the CPU you lose everything in memory. You can dowload the program again when the CPU is repowered, if you have it on your Step 7 PC.

If you are using an EPROM card, and transfering the program with the instruction Copy RAM to ROM, the flash card does not require battery support, and everything loaded to the memory card is retained under all circumstances. If you power down the CPU and restart it, the program in yhe EPROM is read back to the CPU RAM and the program runs in its entirety. But every time you want to download, you must use Copy RAM to ROM. 

When we were working on a client project, we developped it with a RAM card, since testing and medications required multiple downloads, and those are faster with the RAM card. When we were approaching the delivery date, and we needed less downloads, we would switch to a ROM card, for better memory retention.

Hope this helps 

Daniel Chartier 

Thanks Daniel, 

Really is very helpful

Remaining part, if i reset memory ( Ram) with little switch or through ( Reset CPU) through software in Step7-400 , would i loose IP Address with whole program and Cpu would be sent to default IP address or not ? And for this case need to get default Ip address or through MPI to download program again?

Or only i loose everything if battery is faulty and power lost ???

Thanks in advance

Hello;

In my experience, playing with MRES switch does not erase the contents of the memory card on a S7-400.

As you say, if the battery is defective and you lose power  then you lose what is loaded on a RAM card.

Hope this helps 

Daniel Chartier 

Thanks Daniel,

Again it’s very helpful.

What do you think about Mres button and Cpu clear/ reset do with Ram battery type?

In Flash one , it copies Rom to Ram.

But in Ram type what does it do?

I’ve doubt it does something with content of Ram but to which extent ( no idea)

Thanks in advance 

Hello;

As I said earlier, my experience only recalls that if I do a memory reset on a S7-400 with a RAM memory card, I have to be ready to download the program to the CPU, because the RAM will be wiped, both the internal RAM and the RAM card. This does not happen with a Flash memory card.

In all cases, as a standard work procedure, we would do an upload of the program in the Step 7 PC before we did a memory reset. If a download was needed we knew we had the latest version of the program available.

For specific details, this S7-400 manual (Hardware and Installation) will give you detailed information on memory resets:

https://support.industry.siemens.com/cs/ca/en/view/1117849

Hope this helps, 

Daniel Chartier