Simatic Run-Time Meter

DDV · Sep 20, 2006

Good day. I’m having trouble with the simatic sfc2 call (run time meter). I call SFC2, SFC3 and SFC4 in an FC. The run meter output shows that it is running when I activate the set bit in SFC3. My problem is the PV value in SFC2, what is its function? And how do I read the end result in a time base that I can pull to a PC based Operator panel running on Protool?

As always your assistance in this regard will be greatly appreciated.

SimonGoldsworthy · Sep 20, 2006

The PV parameter for SFC2 allows you to preset the run time meter to a value of your choice.

SFC4 returns an integer containing the number of run time meter hours elapsed.

DDV · Sep 20, 2006

Thank you Simon

Thanks. So I can remove SFC 2 if I don’t want to load a preset value?

Does the meter only update in hours?

Amr Hassan · Sep 20, 2006

u will need sfc2 to reset the meter

DDV · Sep 20, 2006

Using a conditional call? As it has no set bit…..

SimonGoldsworthy · Sep 20, 2006

The run time meters count hours. What do you want to do when the count reaches 32767 hours ?

DDV · Sep 20, 2006

Hi Simon.

As it utilizes the processor RTC I was hoping for a bit more from the meter. I will now rather just use timers and counters. I want to display the running and standing times of the machine on the panel in hours, min and seconds. I can do it the long way round, I was just hoping for a quicker more streamline application.

But thanks to both of you for your assistance, I appreciate it.

DDV · Sep 20, 2006

SimonGoldsworthy said:
The run time meters count hours. What do you want to do when the count reaches 32767 hours ?

To answer your question:

The meter will probably never reach that, as we do maintenance every 250 hours or so, the meter will be reset then.

If not:

I would use a comparator to read the word, and then probably at 32000 I would reset the meter. I will then add 32000 to the new meter value into a double integer and just read the value into the HMI over 4 bytes.

Well something like that……lol

And yes I will then probably use SFC2 to reset the meter to 0.

SimonGoldsworthy · Sep 20, 2006

Just for reference, when the run time goes from 32766 to 32767, then when the next hour elapses the run time stays at 32767 but the return value from SFC4 becomes w#16#8081. You could use this to detect overflow and reset the run time to zero with SFC2.

Which CPU are you using. Will you be using OB35 ?

DDV · Sep 20, 2006

315-2dp. No I did not use OB35, I am yet to see how much time I am losing/gaining because of it…if any.

When I do the actual implementation on the machine program, I will call my Blocks in OB35. For now I want to see what effect it has on my code.

SimonGoldsworthy · Sep 20, 2006

DDV - Please find attached the source code for a project that implements 8 run time meters using SFB4, the system block for producting an ON delay. The run times are returned in milliseconds.

DDV · Sep 20, 2006

Thank you very much Simon. I will go thru it tonight.

Simatic Run-Time Meter

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