# Differential Gauge Node, a proposal for a new appearance

I'm using latest Dashboard v. 2.19.4.
Gauges/Donuts work very well when the range minimum value is not negative.
In my case I'm using a dashboard flow to display the electric power exchanged between grid and solar PV panels in my home. When you produce more than you consume the ehchange value is positive ( you are selling energy to the grid), whereas it's negative if you consume more than you produce ( you are buying energy from the grid). So, when setting up the node, a negative value has to be inserted in the minimum field, say -6 kW and +6 kW for the maximum.

In this situation the gauge/donut display is very unintuitive, if not misleading. For instance if no power is echanged (payload =0) you still see half sector filled with color and you may think that half power of total range (-6 kW-6kW) is exchanged while it's actually 0!

As you can see in the following screeshots the gauge rapresentations with power = -5kW, 1kW and +5 Kw are equally not meaningful. For instance, if you are buying 5 kw from grid, you just see a tiny red sector whereas it should be at its almoust maximum extension:

On the right side of every screenshot I have proposed what in my opinion should be the correct representation.
What I'm proposing here is a sort of "differential" gauge.
It should have following behaviour when a negative minimum value is set in the minimum field :

• with value = 0 the needle is in vertical position ( a "zero" digit on central top of gauge would alse be nice to have)
• with value < 0 the circular sector is drawn counterclockwise starting from zero vertical position
• with values > 0 the sector is drawn clockwise from zero.

If not, I'm proposing to the Dashbord/Gauge team to add this new "differential" appearance. From a UI perspective it will suffice to add in existing node configuration window a checkbox "Use differential appearance", enabled only when a negative value is inserted in the Minimum field. So you can keep actual behaviour if you like it more.

HTH
Note: I also had screenshots of 1 kW and 5kW scenarios, but I couldn't post more than two images here. I will if someone is interested in the topic.

2 Likes

interesting - but I think it would need changes to the underlying justgage library first in order to "move" the start point to be your zero point at 12 o'clock.

Hi dceejay,
Glad that you like my idea. Is there a chance that someone will convert this suggestion into an upgrade to current gauge node?

Always a chance... but as I said it would need the Justgage project to pick it up first to allow that to happen.

Would be something that @robertsLando may be interested in.