Wialon for developers User guide API reference unit calc_sensors

calc_sensors

To get sensor values, use the unit/calc_sensors method.

Copied!
svc=unit/calc_sensors&params={"source":<text>,
			      "indexFrom":<uint>,
			      "indexTo":<uint>,
			      "unitId":<long>,
			      "sensorId":<long>,
			      "width":<uint>}

Parameters

Parameter Description
source Source of messages (layer name). If this parameter is empty, the message loader is used by default.
indexFrom Index of the first message.
indexTo Index of the last message.
unitId Unit ID.
sensorId Sensor ID. If set to 0, the values of all sensors are returned.
width Number of items to return. Optional.
This parameter is used when you need a fixed number of aggregated (that is, preprocessed) sensor values. This is particularly useful for generating and zooming in on charts with preprocessed data.
The process works as follows:
  1. The system retrieves all messages within the specified bounds.
  2. The system divides the entire interval into the number of subintervals specified in the width parameter.
  3. Within each subinterval, the system identifies the first recorded sensor value (left), the last recorded value (right), the minimum value (bottom), and the maximum value (top). These values are then combined into the final server response.

The unitId parameter is required even if source is empty. The server uses it to check access rights to the unit and to get the unit sensors. If source is empty, messages are obtained from the message loader, so specify the ID of the unit whose messages are loaded.

Response

If the request with no specified width is completed successfully, a response of the following format is returned:

Copied!
[	/* array of message data */
	{		/* values of sensors from one message */
		<text>:<double|text>,	/* sensor ID: sensor value */
		...
	}
]

If a sensor value can’t be calculated for a message (for example, the message doesn’t contain the parameter used by the sensor), -348201.3876 is returned for this sensor.

If width is specified, a response of the following format is returned. Each sensor is returned in a separate array:

Copied!
[
    [
        {
            "name": <text>,         /* Sensor ID */
            "data": [
                {
                    "left": [<unix_time1>, <value1>],   /* First recorded sensor value in the subinterval and its time */
                    "right": [<unix_time2>, <value2>],  /* Last recorded sensor value in the subinterval and its time */
                    "bottom": [<unix_time3>, <value3>], /* Minimum sensor value in the subinterval and its time */
                    "top": [<unix_time4>, <value4>]     /* Maximum sensor value in the subinterval and its time */
                },
                ...
            ]
        }
    ],
    ...
]

If the request hasn’t been completed, an error code is returned.

Error codes

Error code Description
4 One of the following errors:
  • Invalid input data.
  • Failed to fetch the unit messages.
  • Failed to fetch the unit sensors.
7 The unit doesn’t exist, or the user doesn’t have the View object and its basic properties access right to it.

If you find a mistake in the text, please select it and press Ctrl+Enter.