Problem description:

-I do not understand the concept of Sampling Time in INT_P block. I changed the sampling time But the Integrator Result changed also whats this parameter for and how it should be changed?

Detailed information:

1.Urgency (Technical question)

- this is a Technical question

2. PCS7 version (incl. Service pack, Update version). Also write down if updates are installed for separated products (for example: WinCC, CFC, SFC etc.)

- V8.1 upd1

3.Operating system (incl. Service pack)

- win7

4. Is the application migrated? If yes, from which version?

- No

5. How often does the problem happen (Always/Often/Once/Not applicable)?

-

6.Is there a workaround?

-

7. Did the function/functionality previously work? If yes, did something change recently (Windows update, PCS7 update etc.)?

-

8. MLFB number (in case it applies to hardware)

-

9. Firmware version (in case it applies to hardware)

-

Thank you sir. It was helpful...

Sorry, I use PCS7 V8.1 but that block is in PCS7 LIBRARY V7.1 and the corresponding FB is FB40. 

Explanation of Problem: I have a flow meter and am going to totalize its value using an integrator(I've used INT_P FB40). I have also used a Timer to set the duration of the totalizer(lets say 1hr). 

INT_P has a sampling time which is used in the formula of integration. At the first glance I thought it should be something like Resolution of Integration, however when I changed this parameter, the final result changed. for example, by making it to times bigger, the Integrator result becomes bigger. 

If I set sampling Time equal to the Calling OB(here OB35), everything is fine(if flowmeter gives 3600kg/hr continuously, after 1hr totalizer givers me 3600). If I changed the sampling time to 1sec it gives me 36000 which is ten times of actual value.) 

Please find the attachment.

HI JabbarKamali,

please have a look at the manual of the PCS 7 Library at chapter 2.10.1 INT_P:
"Block INT_P functions by means of sum generation in accordance with the trapezoid rule per sampling interval (SAMPLE_T)."

V(n) = V(n-1) + (SAMPLE_T / (2*TI)) * (U(n) - U(n-1))

The block doesn't know if you call the block every 100ms (OB35) or only one time per second (OB32). And the value SAMPLE_T is auxiliary variable to get this information.
The SAMPLE_T input has the attribute S7_sampletime := 'true' and if you compile and load the CFC to the AS, the SAMPLE_T is set to the cycle time of the OB you have insert this block. So with the SAMPLE_T you can determine how many time is done since the last call of the block.
And by the INT_P block the input SAMPLE_T is used to adjust the value of U to one second.
For example if call the block INT_P in the OB35 (100ms) the value u is multiple with 0.1. And the block is call 10 time in one second, so the result is 0.1 (SAMPLE_T) * u * 10 (times) = v per second.

The value TI is the integration time in seconds and is used for adjustment of the time unit.
For example if you use the unit kg/h you have to set the parameter to 3600, because the SAMPLE_T the blocks calculate the value v to time unit second.

With regards
Heisenberg