accuracy of seconds

[Diogenis]

Hi ALL

How can I rely on the accuracy that has the (SB 3)

Thank you.

Diogenis

[Emil]

SB3 is 1 second generator with 50% duty cycle - halof second ON and half second off. It's updated ruring the scan time. This means, that it's precision is 1 second + up to one scan time.

What do you need to perform? Why the precision of SB 3 is important for you?

[Diogenis]

I want to count how long he worked and how long it was stopped.

That is 2 times. once for ON. And once for OFF

And above about 5 times, for different situations.

It is precisely this way of doing it. ????

Thank

[Emil]

It depends how long are start and stop intervals. Then - what is the pecision you need.

For most of the cases using SB3 is quite good solution.

Some adevices:

- If you want to count seconds, it's better to use SB13, which is positive transition contact of SB3. It gives one scan pulse each second.

- If resolution better than 1 second is needed, you can use SB7 (0.1 sec, 50% duty cycle) or its positive transitionh contact SB15.

If thhe intervalse are long - hundreds and thousends of seconds, maybe it will be better tu use RTC and UTC functions.

[Diogenis]

The nearest thing I want is within 8 hours 5x2 such times. Total 10

If I lose about 1 minute no problem.

But if 1 turned into 10 minutes. I have a serious problem.

The SB7 the work of another, and often have to reset.

The SB13 and SB15 at the Jazz did not work. is empty

I would be very useful one example, the best result.

Thank

Diogenis

[Diogenis]

One question.

If where I put SB3 SB30 - | P | - I will not have precision.

This somehow worked SB30

[Emil]

Sorry - I didn't pay attntion it's Jazz. There you have not UTC, but still RTC. Right - in Jazz/M91 you will use positive transition contact of SB3.

OK - Let's say each time you switch on or off, you can loos up to one second. In your case it seemstheoretically you can loose 10 seconds. Practically I expect this to be within 3-4 seconds total. But - this depends on the scan time of the controller itself.

I don't see any relation between SB 3 and SB30. SB 30 rises when Kyepad entry in sepcific display is completed. It has nothing ot deal with time measuring.

[Diogenis]

Sorry.

No SB30 but SI30

The positive rise of the RTC

[Joe Tauser]

You may want to reconsider your logic to use the actual RTC clock values. Snapshot these when you want to start and stop your timing and then subtract the snapshots to get the actual time. Using the RTC will get you a worst-case inaccuracy of about one minute per month.

Joe T.

[Diogenis]

First of all thank those involved.

The nearest thing I want is for 8 hours after I put zeros again.

But if the RTC has planned an example would help me a lot.

Thank you.

Diogenis