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How much program memory is used for "F" safety functions ?

Created by: @JesperMP at: 4/10/2006 9:35 AM (6 Replies)

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4/10/2006 9:35 AM	Rate (0)
@JesperMP Posts: 54 Rating: (5)	Hi, I saw an example with an "F" safety application. I noticed that the required work memory was 28kB "without program code" and 32kB "with program code". I take that the 28kB is the basic memory requiremnt for the "F" function blocks, and the difference (4 kB) is what is required to implement the program code for the single safety function in the example. Does that mean that the memory requiremt is approximately 28kB + (4 kB x number of safety "objects") ? Or does someone else have an idea how to estimate the approximate memory requirement for "F" applications ?
@JesperMP Posts: 54 Rating: (5)
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4/10/2006 7:11 PM	Rate (0)
Morten Bronze Member Joined: 9/27/2005 Last visit: 4/26/2024 Posts: 203 Rating: (32)	Hallo JesperMP, in theses examples there is only an overview about the memory, but depends on the example which you view. 28kB work memory withoutcode and 32kB work memory with code shall only give a feeling about the memory. But 28kB + 4kB x (number of safety objects) is not a common rule. Greetings Morten

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4/11/2006 3:10 PM	Rate (0)
@JesperMP Posts: 54 Rating: (5)	I know that it is only a rough estimate. That is OK for me. But what if I have 20 safety "objects" ?Or a 100 ? If the memory usage is like 20 times 4kB, or 100 times 4 kB then I will use a considerable amount of memory. Any idea how much memory it will use ? Maybe this is no problem at all. I just dont want to find out too late if it is.
@JesperMP Posts: 54 Rating: (5)
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4/11/2006 5:15 PM	Rate (0)
Morten Bronze Member Joined: 9/27/2005 Last visit: 4/26/2024 Posts: 203 Rating: (32)	Maybe the following link is helpful for you. Chapter 10.5: "Work Memory Requirement for Safety Program" http://support.automation.siemens.com/WW/view/en/22099875

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4/12/2006 10:21 AM	Rate (0)
@JesperMP Posts: 54 Rating: (5)	I have to admit that the chapter 10.5 in that manual didnt make any sense at all to me. I think that to understand it requires a good knowledge of F safety programming, which I dont have at the moment. I am at the stage of evaluating if this is a way to go or not. Therefore I need to have a rough idea of the memory requirement. Let me ask in another way: If I have 5 groups of machinery that each is stopped by one safety circuit, and there are 4 E-stops or other safety monitoring devices per group (giving 5 x 4 = 20 devices in all), how much memory would that take up ? As I said just an approximate estimate is enough to give me an idea about it.
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4/20/2006 6:03 PM	Rate (0)
Morten Bronze Member Joined: 9/27/2005 Last visit: 4/26/2024 Posts: 203 Rating: (32)	You cannot say for example:"For programming one emergency stop, I need xxx kB memory". There are different ways for a solution, in case of emergency stop, you canrealize it with RS-Flip-Flop or you use the FB F_ESTOP1 for a stop category 1. Both solutions are possible but consist different memory space. It depends on your program solution. If you have such a solution then it is easier to estimate the memory space.

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4/24/2006 5:04 AM

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Most of the work memory is used for the automtically generated FB's and DB's. This depends on the number of F-I/O modules in your configuration and the program. Each F-I/O is allocated one DB.
A rough calculation is as follows.

Approximate Work Memory if the program is located in one FB.
=
Use a base work memory of 31kB
+
For each module N*600 bytes
+
Total Number of output coils in the F-ladder N*30bytes
+
Total Number of contacts in the F-Ladder N*40bytes
+
If you have F-Ton use a value of 1400bytes for the first F-Ton and 200 bytes for each extra F-TON
+
If you have 2-hand use a value of 1202 bytes for the first 2-Hand and190 bytes for each extra
2-Hand
+
If you have F-Muting use a value of 2982bytes for the firstmuting and 262 bytes for each extra Muting Block

You can estimate the number of contacts and coils. For each F-DO output multiply by 2 or 3. If you have 5 output modules then 5x3=15 coils.
You normally do not not have more than 6 contacts per rung therefore 6x15=90 contacts.
This will give you a very rough work memory. For the Micro memory card simply mutliply this value by 2.
[:D]

	IM151-7F	NEW IM151-7F	315F V1	315F V2	317F
Total Work Memory	48000 bytes	64000 bytes	128000 bytes	192000 bytes	512000 bytes

I hope this helps

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Created by: @JesperMP at: 4/10/2006 9:35 AM (6 Replies)

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