flow example for bar chart to track number of starts daily please?

Is there an example somewhere for a bar chart to track number of starts daily?
We have a machine that we would like to have a bar chart that shows how many starts it does daily,
so one new bar for each day that shows number of starts as bar and a number count.
We are so far unable to accumulate the payload count in a bar chart.
We are now sending a `number:1` to the bar chart every time it starts, but the chart does not add, but creates a new bar for each payload.

Is there any flow example or good starting point out there please? Many thanks!