Combining pressure and radar sensor

2 water level sensors can be connected simultaneously and operated in parallel. The readings from both sensors are recorded continuously. A defined threshold value determines which of the two readings is used as the primary water level. This allows the advantages of both measurement methods to be combined when using a hydrostatic sensor and a radar sensor together, thereby achieving optimal coverage of the water level range to be monitored.

Mounting situation

 

1 Mounting height (radar)
2 Radar sensor
3 Distance to surface measured
4 Calculated water level
5 Pressure probe
6 Mounting height (pressure probe)

In this example, the pressure probe should be used as the primary sub level sensor. Under normal conditions, however, the water level is significantly below the mounting height of the pressure probe. In this case, the readings from the radar sensor are used for the main water level. During rainfall, the water level rises, submerging the pressure probe. From this point onwards, the pressure probe’s readings can be used for the main water level. As only water level sensors with absolute pressure measurement are currently supported, an additional sensor is required for this example to measure atmospheric pressure.

The first step is only necessary if you intend to use at least one sensor with Modbus interface

  1. Enable the Modbus interface and select the settings for the interface to match your sensors (see Device settings , tab "Interfaces").
  2. Enable the sensor supply, select the voltage level and the duration for which the sensor supply is switched on prior to measurement in accordance with your sensors (see Device settings , tab "Sensor supply).
    Note: There is only one sensor supply available. Therefore, the settings must be selected so that they are suitable for all the sensors in use. 
  3. Configure the measurement channel that will be used to record the reading from the radar sensor. You can use one of the 3 Modbus measurement channels or one of the 2 universal inputs for this purpose.

    You should configure the following settings if you wish to use a Modbus measurement channel (see Sensor settings):

    1. Use "Radar" name for the measurement channel (recommended)
    2. Set the "Mode" to "On" to activate the measurement channel.
    3. Select "Distance" for the "Type"
    4. Configure "Slave address", "Modbus address" and "Function" in such a way that the measurement value can be read from the sensor.

    You should configure the following settings if you wish to use a universal input (see Universal channel):

    1. Use "Radar" name for the measurement channel (recommended)
    2. Set the "Mode" to "0-20 mA" or "4-20 mA" to activate the measurement channel.
    3. Select "Distance" for the "Type"
    4. Configure the scaling via the "0 mA" and "20 mA" fields.
    5. Make sure that "Offset" and "Trimming" are set to 0
  4. Configure the measurement channel that will be used to record the reading from the pressure sensor. You can use one of the 3 Modbus measurement channels or one of the 2 universal inputs for this purpose.

    You should configure the following settings if you wish to use a Modbus measurement channel (see Sensor settings):

    1. Use "Pressure" as name for the measurement channel (recommended)
    2. Set the "Mode" to "On" to activate the measurement channel.
    3. Select "Pressure" for the "Type"
    4. Configure "Slave address", "Modbus address" and "Function" in such a way that the measurement value can be read from the sensor.

    You should configure the following settings if you wish to use a universal input (see Universal channel):

    1. Use "Pressure" as name for the measurement channel (recommended)
    2. Set the "Mode" to "0-20 mA" or "4-20 mA" to activate the measurement channel.
    3. Select "Pressure" for the "Type"
    4. Configure the scaling via the "0 mA" and "20 mA" fields.
    5. Make sure that "Offset" and "Trimming" are set to 0
  5. Configure the measurement channel that will be used to record the reading from the atmospheric pressure sensor. You can use one of the 3 Modbus measurement channels or one of the 2 universal inputs for this purpose.

    You should configure the following settings if you wish to use a Modbus measurement channel (see Sensor settings):

    1. Use "Atmospheric pressure" as name for the measurement channel (recommended)
    2. Set the "Mode" to "On" to activate the measurement channel.
    3. Select "Pressure" for the "Type"
    4. Configure "Slave address", "Modbus address" and "Function" in such a way that the measurement value can be read from the sensor.

    You should configure the following settings if you wish to use a universal input (see Universal channel):

    1. Use "Atmospheric pressure" as name for the measurement channel (recommended)
    2. Set the "Mode" to "0-20 mA" or "4-20 mA" to activate the measurement channel.
    3. Select "Pressure" for the "Type"
    4. Configure the scaling via the "0 mA" and "20 mA" fields.
    5. Make sure that "Offset" and "Trimming" are set to 0
  6. Configure the sub level that you wish to use as "Level - Distance". (see Sub Level settings
    1. Use "Level - Distance" as name for the sub level (recommended)
    2. Select the setting "Distance" for the "Mode"
    3. Select the measurement channel configured in step 3 (i.e. "Radar") from the dropdown list "Sensor List"
    4. Enter the mounting height of the radar sensor in the appropriate field
  7. Configure the sub level that you wish to use as "Level - Pressure". (see Sub Level settings
    1. Use "Level - Pressure" as name for the sub level (recommended)
    2. Select "Absolute pressure compensated" for the "mode"
    3. Select the measurement channel configured in step 5 (i. e. "Atmospheric pressrue") from the dropdown list "Air Pressure"
    4. Select the measurement channel configured step 4 (i.e. "Pressure") from the dropdown list "Medium Pressure"
    5. Enter the mounting height of the pressure probe in the appropriate field
    6. Enter the "Minimum Infiltration Height" in the appropriate field (optional)
  8. Configure the main level (see Main Level settings)
    1. Use "Level " as name for the main level (recommended)
    2. Select the sub level configured in step 7 (i.e. "Level - Pressure") as "Primary Sub Level"
    3. Set the "Threshold of Primary Sub Level" to the level at which the "Level - Pressure" sub level (i.e. the pressure probe) should be used as the main level. Until this threshold is reached, the "Level - Distance" sub level (i.e. the radar sensor) will be used as the main level.