<![CDATA[How to implement metadata?]]>I have a Data point from a MODBUS device that I read on a periodic basis.
The raw data from the device must be run through a calculation in order to display in the graphical view widget.

I was trying the Metadata data point and was not able to get it to work.
my calculation is simple in javascript:
var my = (p1-640)/16.0;
return my;

does not seem to work, meaning the graphical widget does not update.

What am I missing, is there an example similar to this?

]]>https://forum.mango-os.com/topic/2552/how-to-implement-metadataRSS for NodeTue, 15 Sep 2026 06:10:12 GMTFri, 18 Nov 2016 14:46:35 GMT60<![CDATA[Reply to How to implement metadata? on Fri, 18 Nov 2016 18:43:01 GMT]]>OK, cool, I will try that as well...Thanks!

]]>https://forum.mango-os.com/post/13298https://forum.mango-os.com/post/13298Fri, 18 Nov 2016 18:43:01 GMT<![CDATA[Reply to How to implement metadata? on Fri, 18 Nov 2016 16:13:05 GMT]]>No problem! Just so you know, these calculations could probably be performed in the modbus point locator, which would probably be more efficient. It's value*multiplier + additive, so

(value-640)/16 --> value*.0.0625 - 40 would be equivalent, so multiplier=0.0625 additive=-40 but there can be benefits to using a Meta point, if you're wanting to keep the raw values around too for some reason.

]]>https://forum.mango-os.com/post/13295https://forum.mango-os.com/post/13295Fri, 18 Nov 2016 16:13:05 GMT<![CDATA[Reply to How to implement metadata? on Fri, 18 Nov 2016 15:29:22 GMT]]>I see, working now....Thanks!

]]>https://forum.mango-os.com/post/13294https://forum.mango-os.com/post/13294Fri, 18 Nov 2016 15:29:22 GMT<![CDATA[Reply to How to implement metadata? on Fri, 18 Nov 2016 15:12:04 GMT]]>Hi tcontrada,

i would have written that as

return (p1.value - 640)/16.0;

the "my" would probably be aliasing the variable name for the point to refer to itself, and one should call for the .value property of the context point.

I do not know what you mean, "does not seem to work, meaning the graphical widget does not update." but I suspect the problem is the same. Check it on the data point details page if you are making a custom dashboard, just so one can more easily know where things are going wrong.

]]>https://forum.mango-os.com/post/13293https://forum.mango-os.com/post/13293Fri, 18 Nov 2016 15:12:04 GMT