OB3x cyclic time of diff. CPU s7-1500 series. Lower bound.

Greetings,

I have looked through characteristics of 1500 series. Different sizes of memories - that is clear.

But frankly speaking a section in manual called 'CPU processing time' and a term called 'bit operation' says me nothing, due to I have no experience with bit operations or so. Who knows how performs bit operations measurement in lab!?

So could anyone tell me about your plc such as 1513, 1515, 1516 and maybe 1517?

I'm interested in two simple events, for example, OB3x, parameter called 'cyclic time'.

What is lower bound for cyclic time of mentioned above types when:

• plc is running without any going to stop;
• plc is running without going to stop even then when you are going online.
  

Of course it's supposed that your plc isn't loaded by non-digestible program or so.

Also, please don't provide any Siemens quotes from manuals.

• I have got them too.
  
• I would like to have any knowledge based on you own practical experience.

Thank you!

CaOd

If you have more questions .... don't hesitate.

regards
CaOd

 I have concrete questions and I can repeat them.

I'm interested in two simple events, for example, OB3x, parameter called 'cyclic time'.

What is lower bound for cyclic time of mentioned above types when:

• plc is running without any going to stop;
• plc is running without going to stop even then when you are going online.
  

Of course it's supposed that your plc isn't loaded by non-digestible program or so.

Also, please don't provide any Siemens quotes from manuals.

• I have got them too.
  
• I would like to have any knowledge based on you own practical experience.

Thank you!

CaOd

I program things with a OB3x-cycle with 2 ms at a 1516 and it works, also when you go online.

Tell me about this!

Such a monster (with price over 3.8k Euro) simple must run OBs at range below 1ms.

CaOd,

as I understood the library itself is not freely available. Or?

BR

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Update

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OK, I guessed by myself that library is kindly provided and had gotten that in my project. Then I tried to follow the manual steps.

But, in the manual, no words.... It needs to have a special capability to screw up such a simple manual.

What does really mean "access"? Who wrote this [snip]?

BR

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Update

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Also I followed the steps in Chapter 2.2.2.

TIA portal makes a mistake while compilation. And I agree with it.  Two functional blocks cannot be with the same DB. But  it's written and shown in manual!

Hello,

This is not [snip] - it is the truth of life - it is really very difficult to calculate the controller cycle time

Read my answers on topic about the 400 series of controllers:

Absolute minimum scan cycle time

All calculations are mainly reduced to approximate calculations.

If you have there is accurate data on how much and what instruction takes the PLC -  are you sure that you can calculate all of them ???

I am sure that the calculation of the instructions inside the block is possible, but not always advisable.

Here is an example

You Snooze, You Lose: Measuring PLC Cycle Times under Attacks

Testing on a simulator does not provide accurate data - yes, unfortunately it is)

Review the FAQ below:

SIMATIC S7-1500 Profiling

SIMATIC S7-1500, S7-1500R/H, ET 200SP, ET 200pro Cycle and response times

With S7-1200/S7-1500, how do you measure the total cycle time of an organization block?

Topic:

Cycle time of previous OB1 scan (milliseconds)

For example, you can use the instruction "RUNTIME" - to measure the execution time of a block.

Based on this intuition built -> SIMATIC S7-1500 Profiling

Of course, you can not worry - and immediately buy a powerful and expensive PLC (if the customer is willing to pay for it)

Or try to calculate with the help of a simulation and your common sense - chose what you need)

I hope if my opinion help you

Unreality

Hello,

This is not [snip]- it is the truth of life - it is really very difficult to calculate the controller cycle time

Regarding [snip]. The author easily could use various English words and expressions like.

• copy to
• place in
  
• lay
• settle

• put in
  

Totally don't understand what means word "access" in this case!

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Update

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Also I followed the steps in Chapter 2.2.2.

TIA portal makes a mistake while compilation. And I agree with it.  Two functional blocks cannot be with the same instance DB. But  it's written and shown in manual!

BR

Oooooook, but:

For the future:

If something is not clear to you in the manual in which of the languages - always refer to the source - German language (it is in it that constitutes the majority of manuals)

See:

ENGLISH

Access the "FB_Record_Profile" FB after the program code whose runtime you want to measure. Use the same instance DB, e.g. "DB_OB1".

Deutsch

Rufen Sie den FB "FB_Record_Profile" nach dem Programmcode auf, dessen Laufzeit Sie messen wollen. Verwenden Sie denselben Instanz-DB, z. B. "DB_OB1"

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When translated from German to English, the word "Rufen" means - a call.

In other words, call the block “FB_Record_Profile” after when, which you want to measure.

What about  the second part of the problem?

Have you tried to compile two identical FB with the same instance DB?

BR

Hello, i can't SIM this project...

But:

See an example in the attachment.

Excerpt from the manual:

For a loadable cycle analysis at least each of the cyclically called OBs have to be measured (e.g. OB1, OB3x, OB61..).

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Try to measure on a real PLC - each organization block individually.

Then, all at once - by successive measurements.

Helped than he could, as they say)))