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Simple Gauge Example
The cylinder gauge is a real-time chart, which can update its data after specified intervals, without requiring any page refreshes. In this section, you will be shown how you can create a simple cylinder gauge.
Creating a Simple Cylinder Gauge
We will create a cylinder gauge that monitors the diesel level in the generator. This gauge will have a maximum capacity of 110 liters and we will configure it show that 75 liters of diesel is left in the generator.
To create a cylinder gauge, you need to:
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Define the upper and lower limits for the gauge. The limits are displayed on the vertical scale to the left/right of the cylinder. For our example, the lower limit will be 0 and the upper limit will be 110 liters.
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Decide the visual properties of the gauge. This involves customizing the elements of the gauge.
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Decide the gauge value along with the fill color code. For our example, the gauge value is 75 liters.
 
The final gauge looks like this:
Given below is the list of attributes, belonging to the chart object, used to create a simple cylinder gauge:
| Attribute Name | Description | 
|---|---|
  | 
It is used to specify the lower limit, or the minimum value, of the gauge scale, eg. 0.  | 
  
  | 
It is used to specify the upper limit, or the maximum value, of the gauge scale, eg. 100.  | 
  
  | 
It is used to specify the label to be displayed with the lower limit value on the gauge scale, eg. Empty.  | 
  
  | 
It is used to specify the label to be displayed with the upper limit value on the gauge scale, eg. Full.  | 
  
  | 
It is used to specify the character(s) that will be appended to the end of a number, eg. ltrs.  | 
  
The data structure needed to create this simple cylinder gauge is given below:
{
    "chart": {
        "theme": "fint",
        "caption": "Diesel Level in Generator",
        "subcaption": "Bakersfield Central",
        "lowerLimit": "0",
        "upperLimit": "120",
        "lowerLimitDisplay": "Empty",
        "upperLimitDisplay": "Full",
        "numberSuffix": " ltrs",
        "showValue": "0",
        "chartBottomMargin": "45"
    },
    "value": "110",
    "annotations": {
        "origw": "400",
        "origh": "190",
        "autoscale": "1",
        "groups": [
            {
                "id": "range",
                "items": [
                    {
                        "id": "rangeBg",
                        "type": "rectangle",
                        "x": "$canvasCenterX-45",
                        "y": "$chartEndY-30",
                        "tox": "$canvasCenterX +45",
                        "toy": "$chartEndY-75",
                        "fillcolor": "#6caa03"
                    },
                    {
                        "id": "rangeText",
                        "type": "Text",
                        "fontSize": "11",
                        "fillcolor": "#333333",
                        "text": "80 ltrs",
                        "x": "$chartCenterX-45",
                        "y": "$chartEndY-50"
                    }
                ]
            }
        ]
    }
}There! You have now seen how you can create a simple cylinder gauge to monitor the fuel levels.