Ignition Perspective 8.3 Power Chart

Hi,

How can I rotate the unit label ("value")?

You can rotate the axis label using a transform CSS style eg:

transform: rotate(0deg) translateX(-10px);
Here is an example axis definition:

Example Axes Definition
axes[0]{
          "name": "Default",
          "position": "left",
          "width":  120, --> Modify this depending on the length of the label
          "color": "#757A7F",
          "dataFormat": "0,0.##",
          "range": {
            "auto": true,
            "min": "",
            "max": ""
          },
          "label": {
            "text": "Something Really Long",
            "offset": 55, --> Modify this to adjust Y position
            "font": {
              "color": "#757A7F",
              "size": 10
            },
            "style": {
              "classes": "",
              "transform": "rotate(0deg) translateX(-10px)" --> Modify the X translate for X Position.
            }
          },
          "tick": {
            "color": "#757A7F",
            "count": "Auto",
            "label": {
              "format": "Auto",
              "font": {
                "color": "#757A7F",
                "size": 10
              },
              "style": {
                "classes": ""
              }
            },
            "style": {
              "classes": ""
            }
          },
          "grid": {
            "visible": false,
            "color": "#757A7F",
            "opacity": 0.9,
            "dashArray": 0,
            "style": {
              "classes": ""
            }
          },
          "style": {
            "classes": ""
          }
        }

Few things to keep in mind.

  1. Given the power chart allows users to define the axes you might want to consider putting these style overrides in the advanced style sheet.
Example style sheet override

Note: this override is for a time series chart and not power chart your styles will vary

/* Makes the left axis labels on time series chart appear on top */
#simpleTrendRealtime text.ia_timeSeriesChartComponent__yAxis__label[y="-50"],
#simpleTrendHistorical text.ia_timeSeriesChartComponent__yAxis__label[y="-50"] {
    transform: rotate(0deg) translateY(35px);
    text-anchor: end;
}
/* Makes the right axis labels on time series chart appear on top */
#simpleTrendRealtime text.ia_timeSeriesChartComponent__yAxis__label[y="40"],
#simpleTrendHistorical text.ia_timeSeriesChartComponent__yAxis__label[y="40"] {
    transform: rotate(0deg) translateY(-55px);
    text-anchor: start;
}
2. The above style is for left axis you will have to modify the translates for right axis.

Hopefully, this gives you a starting point to work from.

Thank You, but the label is disappearing no matter what value of translateX I use

You might not have added offset to shift the label down after rotating it.
The following is an example of how to apply the mentioned style: