Decagon CTD-10 module

Introduction

The Decagon CTD is implemented as a sub-classes of the SDI12Sensors class. It requires a 3.5-12V power supply, which can be turned off between measurements. While contrary to the manual, they will run with power as low as 3.3V.

Sensor Datasheet

Documentation for the SDI-12 Protocol commands and responses for the Decagon CTD are archived in the ModularSensors wiki.

Build flags

Sensor Constructor

Example Code

The Decagon CTD-10 is used in the menu a la carte example.

#include <sensors/DecagonCTD.h>

// NOTE: Use -1 for any pins that don't apply or aren't being used.
const char*   CTDSDI12address   = "1";  // The SDI-12 Address of the CTD
const uint8_t CTDNumberReadings = 6;    // The number of readings to average
const int8_t  CTDPower          = sensorPowerPin;  // Power pin
const int8_t  CTDData           = 7;               // The SDI-12 data pin

// Create a Decagon CTD sensor object
DecagonCTD ctd(*CTDSDI12address, CTDPower, CTDData, CTDNumberReadings);

// Create conductivity, temperature, and depth variable pointers for the CTD
Variable* ctdCond = new DecagonCTD_Cond(&ctd,
                                        "12345678-abcd-1234-ef00-1234567890ab");
Variable* ctdTemp = new DecagonCTD_Temp(&ctd,
                                        "12345678-abcd-1234-ef00-1234567890ab");
Variable* ctdDepth =
    new DecagonCTD_Depth(&ctd, "12345678-abcd-1234-ef00-1234567890ab");

Classes

class DecagonCTD

The Sensor sub-class for the Decagon CTD-10 conductivity, temperature, and depth sensor.

class DecagonCTD_Cond

The Variable sub-class used for the conductivity output from a Decagon CTD-10 3-in-1 water level sensor..

class DecagonCTD_Temp

The Variable sub-class used for the temperature output from a Decagon CTD-10 3-in-1 water level sensor..

class DecagonCTD_Depth

The Variable sub-class used for the depth output from a Decagon CTD-10 3-in-1 water level sensor..

Defines

#define CTD_NUM_VARIABLES = 3

Sensor::_numReturnedValues; the CTD can report 3 values.

#define CTD_INC_CALC_VARIABLES = 0

Sensor::_incCalcValues; we don't calculate any additional values.

Sensor Timing

The sensor timing for a Decagon CTD-10

#define CTD_WARM_UP_TIME_MS = 500

Sensor::_warmUpTime_ms; maximum warm-up time in SDI-12 mode: 500ms.

#define CTD_STABILIZATION_TIME_MS = 0

Sensor::_stabilizationTime_ms; the CTD is stable as soon as it warms up (0ms stabilization).

#define CTD_MEASUREMENT_TIME_MS = 500

Sensor::_measurementTime_ms; maximum measurement duration: 500ms.

#define CTD_EXTRA_WAKE_TIME_MS = 0

Extra wake time required for an SDI-12 sensor between the "break" and the time the command is sent. The CTD requires no extra time.

Conductivity

The conductivity variable from a Decagon CTD-10

• Range is 0 – 120 mS/cm (bulk)
• Accuracy is ±0.01mS/cm or ±10% (whichever is greater)

#define CTD_COND_RESOLUTION = 1

Decimals places in string representation; conductivity should have 1.

0 are reported, adding extra digit to resolution to allow the proper number of significant figures for averaging - resolution is 0.001 mS/cm = 1 µS/cm

#define CTD_COND_VAR_NUM = 2

Sensor variable number; conductivity is stored in sensorValues[2].

#define CTD_COND_VAR_NAME = "specificConductance"

Variable name in ODM2 controlled vocabulary; "specificConductance".

#define CTD_COND_UNIT_NAME = "microsiemenPerCentimeter"

Variable unit name in ODM2 controlled vocabulary; "microsiemenPerCentimeter" (µS/cm)

#define CTD_COND_DEFAULT_CODE = "CTDcond"

Default variable short code; "CTDcond".

Temperature

The temperature variable from a Decagon CTD-10

• Range is -11°C to +49°C
• Accuracy is ±1°C

#define CTD_TEMP_RESOLUTION = 2

Decimals places in string representation; temperature should have 2.

1 is reported, adding extra digit to resolution to allow the proper number of significant figures for averaging - resolution is 0.1°C

#define CTD_TEMP_VAR_NUM = 1

Sensor variable number; temperature is stored in sensorValues[1].

#define CTD_TEMP_VAR_NAME = "temperature"

Variable name in ODM2 controlled vocabulary; "temperature".

#define CTD_TEMP_UNIT_NAME = "degreeCelsius"

Variable unit name in ODM2 controlled vocabulary; "degreeCelsius" (°C)

#define CTD_TEMP_DEFAULT_CODE = "CTDtemp"

Default variable short code; "CTDtemp".

Water Depth

The water depth variable from a Decagon CTD-10

• Range is 0 to 5 m or 0 to 10 m, depending on model
• Accuracy is ±0.05% of full scale

#define CTD_DEPTH_RESOLUTION = 1

Decimals places in string representation; depth should have 1.

0 are reported, adding extra digit to resolution to allow the proper number of significant figures for averaging - resolution is 2 mm

#define CTD_DEPTH_VAR_NUM = 0

Sensor variable number; depth is stored in sensorValues[0].

#define CTD_DEPTH_VAR_NAME = "waterDepth"

Variable name in ODM2 controlled vocabulary; "waterDepth".

#define CTD_DEPTH_UNIT_NAME = "millimeter"

Variable unit name in ODM2 controlled vocabulary; "millimeter".

#define CTD_DEPTH_DEFAULT_CODE = "CTDdepth"

Default variable short code; "CTDdepth".