Are there anyone else that will be using the new IM151-8 CPU ?

[Rich1955]

Well so far I'm up to $6000 USD and counting for the system, 1/2 of that is software!!!!!!!!!

 

[twu026]

Does anyone know if the IM151-8 accepts non-Siemens MMC?

 

[ArikBY]

No Way
Far as I know you need original MMC.
Search the forum for MMC,there is some threads about.
The MMC is about 10% of the price of the CPU IM151-8.
I know it irritating,but take it as a package(CPU+MMC).
Even the MMC price the package is cheap.

 

[twu026]

Oh well, might need to shell out money and get a bigger Siemens MMC - damn you $iemens, I shake my fists are you.

The 512K MMC card that came with the PLC is not going to be big enough for me. I have only written a few functions and I have already used up half the card.

***** RANT_MODE := TRUE; *****

At first I thought my eyes was playing tricks on me. How can I fill up a 512MB MMC card?!
Who knew people still make 512K (0.5MB) MMC card these days? What is the point of that anyway, it is just plain wasteful. Even a floopy has more storage capability.

But what really annoys me is not the fact that I have to buy a bigger MMC card. What annoys me is that I have to buy a Siemens MMC.

It is like adding an ethernet port to your product and then making that RJ45 connector slightly different so people have to buy your specific cable.

I hope we don't end up in a position where we have to have a special MMC card from Vender A, a special SD card from Vender B and a special CompactFlash card from Vender C.

***** RANT_MODE := FALSE; ******

 

[JesperMP]

How can you have used up a 512kB MMC card if the CPU only has 128 kB ?????
I am assuming you are working with the IM151-8. Or are you not ?
I often use 64kB cards because they are so cheap and quite often the program will fit in it.
Are you possibly using the "Save to memory card" function ? If so, this stores also the STEP7 project, comments and symbols and all which explains the amount of storage needed.

As to why Siemens dont support regular "MultiMedia Cards" then I can think of the following reasons:
The S7 CPU is not a PC and thus does not support relatively complex drive formats - such as FAT. It is probably a very simple drive format.
By not allowing consumer grade MMC cards, Siemens avoid the inevitable surge of complaints from inventive (=cheapskate) users with failed cards (and no, consumer grade flash cards should NEVER EVER be used in an industrial application).
That, or they really want to rip us off.

 

[twu026]

I do not understand how the CPU in the IM151-8 fetches the data required to execute the PLC program. Maybe you can enlighten me on this matter JesperMP.
I do not even know what the 128KB memory of the CPU refers to? Is that the cache memory of the CPU?

I do know an Intel Core 2 Duo CPU moves data this way:

Harddrive <-> RAM <-> L2 cache memory <-> L1 cache memory

The whole program is not loaded in the CPU cache during execution, data is moved up the chain when required. As you go up the chain the storage capacity goes down and the access speed goes up.

Are you saying that the whole program has to be less than 128KB so it can be loaded into the CPU cache? Is data not transfered from the MMC to the CPU cache when required?

 

[JRW]

right click on your project blocks folder
GO to Object Properties>Blocks
What does the size in work and load memory say?

 

[twu026]

I disagree with you on the issue of 'consumer grade' MMC.

I do not see how Siemens MMC card is better than the MMC card I can get at my local electronics store. It looks just like any other cheap plastic MMC card to me.

By the way, Schnieder allow standard SD cards in their PLC, you can download the program with comments into the PLC as well as datasheet etc.

 

[twu026]

My 'User program memory' is fairly small, but the 'System data memory' is over 200KB. I am assuming that the 'System data memory' includes the HW Config files etc.

 

[JesperMP]

I do not understand how the CPU in the IM151-8 fetches the data required to execute the PLC program. Maybe you can enlighten me on this matter JesperMP.

Normally, in Simatic Manager you select all blocks and hit "download". If you used the "Save to Memory Card" function, then an archive file with the entire project is stored on the card. I dont know how to delete the archive file, maybe someone else knows. Maybe try to use the CPU reset function with the switch on the CPU.
I completely misunderstood what you asked about. As to the question, I have a vague idea how the innards of an S7 works. What is important in this context is that the program must fit in both Load memory and Work memory. The CPU will load the code and data blocks from Load to Work memory the first time it encounters instructions that address them. After that the code and data will stay in the load memory.
There might well be some kind of cache memory function, but it is transparant to us. On the higher level CPUs there is some onboard CPU cache memory.

I do not even know what the 128KB memory of the CPU refers to? Is that the cache memory of the CPU?

You need to know what is "Load memory" and "Work memory". An IM151-8 has 128 kB work memory. Do not compare a traditional PLC with a traditional PC. Their architectures have nothing in common.

I do not see how Siemens MMC card is better than the MMC card I can get at my local electronics store. It looks just like any other cheap plastic MMC card to me.

That is the cleverest remark I have ever heard. Not.

By the way, Schnieder allow standard SD cards in their PLC, you can download the program with comments into the PLC as well as datasheet etc.

I predict that lots of "smart" Schneider users will try to save a penny on flashcards by purchasing cheap stuff from the local electronics shop. And they will learn how reliable they are the hard way.

 

[twu026]

So, if the program size has to fit in 128kB of CPU memory, then there is no point in buying a MMC that is significantly bigger than 128kB.

Hence that is why the default MMC you get for this CPU is 512kB. That makes sense - thanks for clearing that up.

With regards to the issue of reliability of 'consumer grade' portable storage, that is another issue for another thread.

My point has always been about - choice. If PLC manufacturers choice to use standard technologies in their products, then they should allow us the choice to use standard parts.

Again, this is probably another issue for another thread - so I will leave it at that.

 

[JesperMP]

You do have a choice.
There are 3rd party vendors of Siemens S7 MMC compatible cards. Helmholz and Deltalogic. They are somewhat less expensive, 30% or so.

Dont know about the "default" MMC card for any S7 CPU's. Where do you have this information ?
The most obvious card size is the 128kB (6ES7953-8LG11-0AA0).

 

[twu026]

Maybe I am doing something wrong, but as I stated before my 'System data memory' alone is over 200KB. I am assuming this data memory includes HW Config information.

 

[JesperMP]

I have made a test project with one IM151-8, a slave IM151-3, and configured connections to other stations. The System Data memory is then approx 20 kB.
If I delete the IM151-3, then it drops to approx 3 kB.
So 200kB does sound excessive. Have you defined a lot of local i/o and/or profinet i/o ?
If you cannot directly pinpoint what is the reason, then try to start all over by defining a new IM151-8 station. If you have made some symbols and blocks copy them to the new project.

 

[JesperMP]

Another way to possibly find the reason for the size of the huge SDB block is to doubleclick on the System Data block in the Blocks window in Simatic Manager. A window with a list of all SDB blocks will popup. Hit the Help button in that Window and select Number of System Data block to get a hint for what each SDB is used for.
Possibly one or more SDB blocks will stand out as extra large.