Discontinuous Chart Help

Ignition
1

I’m making a chart for an online gauge I got all the data in but when there is no product the gauge reads zero. This is what I want because I don’t want to display false readings but on the chart in Ignition I would like discontinuities where it goes to zero instead of the messy lines I have now. Any ideas?

2

I’m curious on this one what IA has to say. Please post back if you resolve this.

3

Hi,

I’m going to guess… that there actually is a 0 logged when there is no product data? Is that true? And this is tag history, or transaction groups?

Regards,

4

Yes there is actually a zero logged when there is no data, I am wondering if I can filter out any zeros since it is never a real measurement. This is tag history.

5

Currently there isn’t a way to filter them out, at least when querying through the tag history system. I honestly can’t think of a way to easily avoid them… if you set up the Eng limits of the tag to not allow 0, and then turn on engineering limit enforcement on the low bound, the quality of the tag should will go bad when the value goes to 0, and that should result in a gap in the chart, instead of 0. Not entirely ideal, but it may be a way around for now.

If the tags are used for display and you don’t like the overlays, you can opt out of them on the tag binding screen.

Regards,

6

Are the measurements polled from a device
automatically? The only other way to reduce the ocurrance
of zeros might be to require operator action to ‘take a recording’ of the measurement…that could help insure the values recorded are of actual measurements…

7

Thanks for the responses I will try the engineering limits and see if that gives me a gap, I’ll respond back with what I see.

They are automically polled from an online gauge we have a photoeye that tells us when it is okay to take a real measurement and when to force it to 0.

I’m also curious what would happen if I made a special scan class for this using my photoeye as the driving tag. Could I then use the discontinous type in the dataset tab of the chart customizer so the pen wouldn’t fill in gaps?