For the AMU attributes, changing the scan rate, bad idea?

[WL_10521300]

Hi there,

I have a general question about changing the scan rate from 60000 ms to 1000 ms.  I want to change it because I see that there is a delay (about 30s to 1 min) of updating RunningMCC_Status. Then the attributes I display go out of sync with the timer displayed on the AMU card.  I notice that there is almost no delay when I change the scan rates of the attribute I have assigned as the asset status. Is changing the scan rate a bad idea? I guess what is the cons/pros if I do change the scan rate ?

[mstarnaud · Accepted solution]

Hi

Officially PTC doesn't support changing the scan rate for AMU properties. But while officially it's not supported, I can tell you by experience that a lot of people have done it, it should work it's just not guaranteed. "At your own risk".

For the specific case of the Asset Cards and the RunningMCC_Status and AMUAttribute1Value_MCC properties, putting them as low as 1000ms should not cause issues. But you may find it's not showing the values as fast as they appear in Composer, because of the refresh rate of the Mashup. The Asset Monitoring Mashup has a timer widget to refresh the results and I believe its refresh rate is set to 1 minute. So even if you lower the scan rate to 1 second, I would expect you could see updates in the screen as slow as 1 minute. And to change this, you would need to customize the Mashup (find which Mashup it is, duplicate it, edit the duplicate, then change the link in the menu's SQL table/record). I think that if you leave the original system & scan rate in place, the values can be up to 2 minutes late (1 for the scan rate and 1 for the Mashup's timer).

There is very little risk to lowering the scan rate to 1 second (1000ms), especially for these MCC properties. There may be small performance issues if you have hundreds or thousands of them getting regular updates since the current values are kept in the database. Updating the value in the database takes a little bit of "performance". I can't think of other issues for those properties at the moment.

If you were to modify the original properties, like Temperature instead of AMUAttribute1Value_MCC, there would be a bigger impact. These ones will throw an error if it detects multiple values in the same second. Also they keep the history of all the values and will need to spend the time to process each value and the corresponding alarm condition(s). We have seen many people with too many results (thousands per minute) have performance issues, this often happens when people lower the scan rate on a lot of attributes which get regular updates. This issue only happens with the original properties and not the Asset Card "_MCC" properties, because the Asset Card properties only keep the current value and the only calculation they have is for the running status which is a simple check.