Tag clamp mode not working

Ignition
1

I have a tag that its values are normally in the range of 0 to 5 kg/cm2, but sometimes, when there is a problem with the sensor it goes to 83. This tag is being historized and graphed (its the orange pen):

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Since some other variables have also small values (0 to 5) they cannot be seen on the graph (Not even if I hide the orange pen, the graph doesnt re-scale, but that’s a different story) So I tried to clamp the tag to a value of 6. like this:

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But the result was that the tag still gets a 83 value just for a second or split second and then it gets clamped to 6, but that transient value its still recorded in the graph:

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So, the scaling of the graph is still a problem.

I dont know if that clamping problem might be related to this issue: Tag Clamping / value limiting - #7 by Colby.Clegg

Is that a known bug? My version is 8.1.48

Any solution or workaround?

Thanks!

1 Like
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Clamping only affects writing to the tag, it doesn’t affect the value being read into the tag. If you need to clamp the read value, then you’ll need to do it at the source, or use a derived tag with a clamping expression

1 Like
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Set your engineering limits to 0 and 6, and the engineering limit mode to "Clamp_Both" the tag should go 'Bad Quality' when out of these bounds. You should be able to set the power chart "breakLine" parameter on the pen to discard bad quality data.

3 Likes
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Thank you Nick and David. I’ll try both of your suggestions.